After being saved by Lady Seto, Seina and his colleagues are invited aboard her ship. Seto has an interest in Seina, and in particular his peculiar talent for misfortune. However, a band of pirates that escaped capture by Seto's fleet also have their sights set on the plucky young Earthling.

Seina arrives at Galaxy Police immigration, ready to begin his training. He is surprised to see a familiar face there; Kiriko, his long-time friend and love-interest, is working there as an immigration officer. After a tour of the facilities, Seina moves into his quarters and meets his roommates, but his legendary bad luck has accompanied him!

Seina's roommates aim to make his first night at the Academy a memorable one as they sneak out after curfew to enjoy the nightlife. However, a promising evening turns sour when they get captured, and they soon find themselves being subjected to some rather unorthodox experiments at the hands of a familiar character.

After the official induction ceremony, Seina begins his Galaxy Police training in earnest. However, he finds himself ridiculously outclassed by the other students in speed, strength and stamina. His only hope of being able to cope with the intense training regime is to undergo a high-tech physical enhancement procedure.

Following his body enhancement procedure, Seina needs to grow accustomed to his massively increased strength. Amane arranges for him to move into her house for a few days so he can be supervised continually. However, he won't be alone - Elma and Kiriko are moving in as well!

Seina's body control training continues, but the thought of him and Amane being alone together inspires uncontrollable jealousy amongst their colleagues. As if Seina's training were not made difficult enough by Amane's distracting sexual behaviour, the house-mates have to cope with a visit from Amane's parents who disapprove of her Galaxy Police career.

After completing the first stage of his body control training, Seina is sent off into space aboard a cargo ship along with his fellow students to gain valuable practical training. However, fate (or Seina's luck) conspires against them when the ship's engines fail, leaving them stranded and defenceless in the face of a space pirate attack.

The new trainees are assigned to various divisions of the Galaxy Police for some experience of policing in the real world. Seina, with his unique talent borne in mind, is assigned to the Anti-pirate Decoy Squad. However, Mitoto manages to accidentally lead Seina aboard a military vessel, which promptly comes under attack from the merciless Tarant Shunk and his band of pirates.

Seina is assigned as captain of the Anti-pirate Decoy ship "Kamidake". After another encounter with Seina's mysterious talent for drawing out pirates, the Da Ruma Guild of space pirates decide that enough is enough, and aim to wipe out Seina before he can cause them any more trouble. Meanwhile, the crew of the Kamidake receive their first paycheques, and Seina goes shopping for gifts.

The crew of the Kamidake rescue a man on the run from space pirates, and he asks them to deliver a package to Lady Seto on Jurai. However, the Kamidake comes under attack from space pirates still seeking the contents of the package. The crew are forced to nurse the Kamidake to Jurai the slow way when the hyperdrive is damaged, but the pirates are still hot on their tail, while food and water supplies are running out!

The Kamidake finally reaches Jurai, and the crew is able to deliver the package, which turns out to be a royal tree seed that was missing for thousands of years. Lady Seto has some surprising revelations about Ryoko's past, and Seina meets a strange young girl named Neiju. The Kamidake turns out to be damaged beyond repair, but Seto presents Seina with a new and highly advanced spacecraft.

Seina and his crew escort Neiju back to the Academy, but their mission becomes more dangerous than they expected when they are ordered not to use the ship's weaponry. The girls become fiercely jealous as a result of Neiju's affection towards Seina, but Kiriko discovers that Neiju is not just an ordinary little girl.

Fuku, the creature that acts as the computer in Seina's new spaceship, has difficulty coping with the rigours of combat, so the girls decide to create an artificial replacement. This makes Fuku feel unwanted, and she soon longs to return home, to Earth, to see her creator once again.

Seina and the girls head for Earth for a well-deserved vacation, but they are interrupted by a distress call before they even arrive. The distress call turns out to be a trap set by Tarant Shunk, but they easily escape and reach Earth safely. On Earth, Seina discovers that a few changes have taken place in his absence, and a familiar face from his travels is waiting for him!

During his holiday on Earth, Seina bumps into Tenchi Masaki and his unusual extended family. Seina finds out some surprising details about Tenchi's housemates, and takes Fuku to see her creator, Washu. Meanwhile, Amane, Kiriko and Ryoko help out at the Yamada family convenience store.

When Lady Seto encounters a fleet of space pirates who possess phenomenally good luck, she realises that only one man can counteract their good fortune; Seina Yamada. However, even though Seina and his crew easily defeat the Good Luck Fleet, the Da Ruma Guild is preparing an even more cunning plan.

While the Da Ruma Pirates Guild celebrate their victory over the Kamidake, Lady Seto comes up with a plan to even the playing field a little; bond Kiriko, who is distantly related to the Masaki family of Jurai, with a royal tree, allowing the Kamidake to use its powers.

With Kiriko bonded to the tree Mizuki, the second stage of Seto's plan gets underway. The core unit of Mizuki is merged with the Kamidake to form an even more powerful spaceship. With Seto taking command of the vessel for its first mission, the crew stumble across the top-secret base of the Da Ruma Pirates Guild.

The Da Ruma Guild may be no more, but Seiryo and his ship the Unko are still at large and causing trouble. With no easy way to track him down, Seto and Airi organise a duel between Seiryo and Seina to lure their quarry out.

With the threat of both Seiryo and Da Ruma removed the Anti-pirate Decoy Squad is disbanded, and the Galaxy Army take an interest in the Kamidake. Seina and his crew try to obstruct the transfer when they hear their ship is to be taken from them. The girls are accused of conspiring to hijack the ship when it disappears en route to its new home, and Seina winds up shipwrecked on a remote planet and facing a murderous old foe.

Tarant Shunk's guild of pirates set out to capture Seina, but as he shelters from their attacks with the villagers who took him in, he discovers an ancient and powerful weapon concealed in a cave. Meanwhile, the girls work to clear Seina's name and discover that there is more to the disappearance of the Kamidake than a mere pirate attack.

As Seina returns to life at the Academy, the girls must go their separate ways. However, they soon discover that the Galaxy Police want them to remain together after Seina's graduation. Seina, meanwhile, is summoned to a meeting with the Juraian inner royalty for an amazing revelation about himself that also leads the girls to confront their true feelings for him.

Following the revelations about Seina's position and the girls' feelings for him, it is decided that he should marry all four of them (for purely political reasons, of course...)! However, there are a number of parties that want to interrupt the wedding for one reason or another. Will Seina even make it to the altar unscathed?