I decided to separate these posts by disc. The Complete Anthology keeps the setup of the original discs (as far as I can recall, anyway), complete with original special features (although none of the discs have very much. This first disc only has the clean opening and trailers) and episode count. The episode title given in the subtitles occassionally differs from the actual Japanese, so I've included the subtitle, the actually Japanese, and my translation, if needed.
Episode 1: Mother Returns/Atashi ga Mito! (I'm Mito!)
The series begins with Aoi Mitsukuni remembering one of the few memories he has of his father, the two of them visiting an old castle, and his father giving him a bracelet. Current day, Aoi is 15, his dad has been dead for ten years, and he's waiting for his mother, who works as a supermodel in New York, to come home for her annual visit.
Meanwhile, up in space, the titular space pirate, who looks like a little kid with glasses and a ridiculous ribbon in her hair, pushes her crew to reach their destination, but the entire ship is captured en route by the Galactic Patrol. Not to be held back, Mito puts on a mail suit that makes her look like an adult and races through their captor's ship, looking for the controls. She is detained by Ranban, head of the GP, who demands she give him the seal so he can uphold justice in the galaxy. Initially Mito fights him with a light saber, but then just shoots his weapon out of his hand with the same light saber. However, Ranban manages to get a holo-picture of Aoi from Mito, and makes off with it, driving Mito crazy. In order to escape, her second-in-command, Sabu, exploits a glitch in Mito's mail suit that turns it off, and they get out. Although upset, Mito realizes that she's already late, and takes off on her own in a smaller ship, the Shonagon.
In his shadowy hall, Ranban commands his special officers Masatsuki and Mutsuki Nenga to capture Aoi, Mito's son (although I'm not sure how he knew he was her son just from the picture. Must have intuited it from her reaction).
Back on Earth, and with yet another train not bearing his mother coming and going, Aoi decides to see if his mother somehow made it back to the house without him noticing. He catches Mito sans mail suit there, but he doesn't recognize her and grabs her, thinking she's a thief. She gets away from him. He later finds a newly mail-suited Mito, and asks her if she saw a little girl go by, but Mito feigns ignorance. They go and pay their respects at the grave. While there, Mito sends her son away, sensing the presence of the Nengas. As soon as Aoi is gone, Mutsuki goes to arrest Mito, but Mito instead pulls out a huge bazooka, and the fight is on. Mito leads Mutsuki away from the graveyard and into a construction area. Aoi follows after the trail of shots from their weapons. Mutsuki is overpowered by Mito, so Masatsuki shows up and starts going off on a spiel, but Mito shoots at him mid-sentence, causing him to fall from the precipice he was on. Instead, he debuts Kaizou-kun, a small device that transforms an ordinary construction vehicle into a mecha! (Note: kaizou means 'remodeling.') With the mecha, Masatsuki corners Mito, but just as things look bleakest, Sabu and Shin, her second- and third-in-command arrive and destroy part of the mecha. Mutsuki plans to arrest them all, but then mushrooms suddenly sprout from her hair, giving Shin the time to collapse the mecha completely, which Mito then shoots rapidfire. The Nengas make a quick getaway, and Mito's mail suit starts to malfunction. It opens up and releases her, just as Aoi (who had been watching from a distance) runs up to her, getting an eyeful of her true form emerging.
Episode Two - Call Me Mom!/Kaasan to Yonde!
Picking up precisely where the last episode left off, Mito crawls back into the mail suit and tries to convince Aoi that everything he saw was just a dream. And that might have worked, except that Sabu and Shin are still there. Shin belatedly morphs into a cat. Mito is berated by a floating UFO type of thing that is her mother (who was in the previous episode, but didn't do anything worth mentioning), and so she emerges from the mail suit and tells Aoi the truth. Or starts to, anyway. He faints after hearing "This is my true form." And wakes up later thinking it's all a dream, only he's still dreaming. He wakes up again, but still can't believe his mom is really a little kid. Until he runs into the room full of mail suits...
With Aoi properly awake, it's time for him to hear the official exposition about everything. Sabu is a cyborg and Shin is a nanotechnoid shapeshifter, and the mini-UFO holds the soul of Mito's mother, Sobo. Aoi's still not convinced Mito's not a fake: what about the magazines she was in? Turns out they were faked using Shin's shapeshifting. Mito proves her identity by relating a memory of when Aoi was eight, but it's her story-telling style, not the actual story, that brings it home. Mito also accidently lets it slip about the Galactic Patrol, so Sobo fills Aoi in about the space pirate part of the title. This brings some explanation about the seal, apparently the key to a super weapon. Aoi figures it's the bracelet his dad gave him, but Mito neither confirms nor denies this. Instead, she takes the opportunity to finally embrace her son with her own hands, not the suit's.
The Nengas report back to Ranban, but keep Mito's presence on Earth from him, so they can capture her themselves and bring back glory to their family name that their father somehow lost. This gets elaborated on more as the series goes on, but not until disc three or four, if I recall correctly.
The next day, Aoi leaves the house without telling Mito, or telling her that it's "Take Your Mom to School Day." At school his classmates notice he's down, and the resident rich girl figures its because he has an Oedipus complex. As class begins, a new transfer student is introduced -- Mutsuki Nenga! Aoi, however, is none the wiser.
Meanwhile, Mito cleans Aoi's room while he's at school and finds the flyer for "Take Your Mom to School Day." She runs off in such a hurry that she forgets to put on a mail suit. Fortunately, Aoi covers for her by saying she's a relative of his, and the teacher has her registered for third grade. After school, Mito tries to get Aoi to call her Mom, but it's just not happening.
Aoi is spared some embarrassment by the arrival of Masatsuki and Mutsuki, who use Kaizou-kun on a drink vending machine this time. But Mito takes over a bus (no, really) and calls for backup. She ends up driving on a train track as far as she can go, but the Nengas corner her and Aoi. Sabu arrives with Shin and blows up the mecha, and then Aoi starts to glow. The Nengas eject, and the bridge blows up. When the smoke clears, Aoi is out cold...
Episode Three - Sabu and Shin/Sabu to Shin
The papers report the destruction of the bridge as being due to old age, but Mito's more concerned about getting Aoi to call her Mom. Still unable to say it, Aoi takes off for school early, but without his lunch, causing Mito to chase after him. Sabu is dissatisfied with the arrangement, but Mito would rather let Aoi have a normal life on Earth than take him into space, and she is the captain. So Sabu rails against the boy instead, and Sobo plants the seed of testing Aoi's 'manliness.'
Meanwhile, Mutsuki gets herself ready for school, which means covering herself with aqua-coating to keep out water (which is deadly to her species), and then uses the old "there's something on your shoulder" technique to plant a tracking device on Aoi. She also tries to get information on Mito out of him, but her interegation is interpreted as putting the moves on him by the resident rich girl (who is so much a rich girl that she has her cronies do the Ojou-sama Laugh for her). Mito thinks much the same, having finally caught up with her son, but she is found by Aoi's teacher and taken back to school.
Later, Shin, disguised as the school nurse, hooks Aoi up to a machine and monitors his reactions to a scenerio she describes to him. Sabu, preferring a test with more direct results, teleports with Shin and the boy to the Chunagon (Mito's ship), all witnessed by Mutsuki, who has another mushroom attack.
Up in space, Mito's crew laments the fact that they haven't heard from their beloved Mito since she went to Earth, when Sabu and the others show up. The crew gets a good look at Aoi, who freaks out before being dragged out in an X-wing plane by Sabu. Sabu intends for the flight to make Aoi realize that he and his mom live in totally different worlds, but all Aoi can think about is the classes he's missing. And it doesn't help that the Nengas, lead by the tracking device, start shooting at them. The control panel gets hit, and it goes up in flames, giving Aoi a sudden vision of his mail-suited mother doing something while surrounded by flames (it's hard to tell exactly what). He suddenly grabs the controls and starts steering the plane, screaming like a mad man the entire time. He avoids all the shots from Masatsuki and Mutsuki's ship and even manages to get behind them. No doubt he would have taken them down if the plane hadn't run out of fuel.
The Nengas corner Aoi and the others, but are sent running by the sudden arrival of Mito, who found out about Sabu and Shin's tests from her mother earlier in the episode. And once the danger is over, she's ready to lay out some punishment whip-style on Sabu and Shin, but Aoi covers for them, and Mito lets them off the hook. She officially tells the crew that she'll be staying on Earth for an indefinite amount of time, and leaves the others to have a scene between Aoi and Sabu. Sabu grudgingly admits that Aoi isn't a complete failure, and Shin comments that Aoi is no ordinary boy (to which I say he wouldn't have been, being a half-alien as he is, even without any powers).
Episode Four - Trouble at the Firefly Festival/Taihen na Hotaru Matsuri! (The Terrible Firefly Festival)
The Nengas report to Ranban, making excuses for not having any leads on Mito's son. After the report is over, Masatsuki makes plans to take Aoi hostage to get Mito to surrender herself. Mutsuki has doubts about taking a hostage, but Masatsuki reminds her that it's the only way to bring honor back to their family.
Back with the Mitsukunis, Mito notices that it's the day of the Firefly Festival (the town is known for its fireflies), and tries to coerce Aoi into going with her, even though he already made plans to go with his friends. As he leaves for school, Mito's mother points out that Aoi still hasn't called her Mom yet. Aoi, meanwhile, ruminates while looking at a photo of him and his mail-suited mom while waiting for his friends. They meet up with him, and spy Mutsuki spying on them (well, Aoi), so they all get together and do typical festival things (goldfish catching, shooting prizes, playing shogi, etc.).
While relaxing later on, Mutsuki prepares to stop beating around the bush and capture Aoi, but she's distracted by the sound of her brother (who had been watching in the background) being frightened off by a cat (I haven't mentioned it, but Masatsuki is afraid of cats, like his father. Which is probably why he's the more gung-ho of the two about reclaiming the family pride, come to think of it), and goes off to help him. Aoi's friends, seeing a chance to hook him and Mustuki up, send him after her. All of this is viewed by the resident rich girl, Kafuko, who reveals that she hates/loves Aoi because he refuses to be smitten with her. Which is why she interrupts the two of them, right when Mutsuki was about to capture Aoi. She sends her cronies to scribble on Mutsuki's face, and with attack imminent, Mutsuki yet again reaches for her gun, only for Aoi to take down the two girls himself and tell Mutsuki to run for it. Kafuko is about to go after the girl when the voice of their teacher (in a nearby tree) distracts her, and Aoi gets away, as well.
As the two reach a safe distance, Aoi realizes he's been holding Mutsuki's hand and blushes. Mutsuki wonders why her heart is pounding so fast... (maybe because you were just running?) As the day turns into evening, Aoi and Mutsuki continue to spend time together. Their conversation turns to their mothers, with Mutsuki confiding in Aoi that her mother is bedridden (then immediately wondering why she told him that). She also realizes, from that way he talks about his mother, that he didn't know Mito was a space pirate until recently, and starts to feel a little sympathy for him. Not only that, but she gets an attack of mushrooms and runs off, clutching her head. Fortunately, she manages to pull out all the mushrooms before Aoi catches up with her. Tired of running around, Mutsuki screws up her courage to capture Aoi once and for all, but finds that she somehow mislaid her gun. Which is when mail-suited Mito finally finds Aoi and drags him off. Outwardly, she is polite to Mutsuki (who introduces herself by name, but didn't she give Mito her name as a Galactic Patrol member in the first episode?), but inwardly she is seething that Aoi blew her off to apparently go on a date. And that's when Masatsuki, finally free of the cat, crawls up and sees his sister with Mito. He instantly leaps into action, using Kaizou-kun to make a streetlamp mecha. Mito calls on Sabu and Shin to take down the mecha while Aoi gets Mutsuki to safety. While Mito enters the fray, Aoi and Mutsuki run down the stairs while those gate things fall over like dominoes, but they manage not to be crushed. But a falling lamp does clock Mutsuki on the head before the fight is over. (Masatsuki is over powered, of course.)
Seeing Mutsuki hurt, Aoi chews out his mom for getting her involved, but when Mito comes out of the mail suit to express her regret, Aoi tells her that he cannot accept her as his mother. To him, she's still just a fake wearing his mom's face. Hurt, Mito runs off, while Sabu explains that the captain just wanted Aoi to call her mom, and thought the mail suit would help. Aoi takes Mutsuki to the first aid tent, and then finds his mom crying by the river. As the fireflies come out, she tells him this is a special spot she and his father used to go to. She asks if he wants to hear more, and he says yes, but the episode ends before she actually does, setting up for the next episode to be an entire flashback. But that's on the next disc.