The manga was serialized in Akita Shoten's Young Champion magazine from June 1998 to August 1999, spanning 3 tankōbon volumes.

Both the manga and anime are noted for their moe art style and heavy violence despite the young main characters, Pokémon-like monster designs, and initial appearances of a slice-of-life-esque series.

Central Park Media filed for bankruptcy in 2009, and the DVDs and manga volumes subsequently went out of print in North America.

To make matters even worse for Yuri, the only way to capture the aliens is to adjoin with a Borg, a symbiotic life-form whose sole purpose is to protect their host as well as incapacitate and capture other aliens, using anything available to their arsenal (which includes, but is not limited to: Borgs, inline roller blades, knee pads, tranquilizer dart guns, and lacrosse sticks.)

She finally collapses at Miyu's feet on her knees in tears, her own Borg dying due to the overreaction and falling off her head.

As a result of the incident, Ms. Hisakawa is rebuked by the headmistress of the school, Ms. Okada (another Borg-fused human), and informed that she may even be replaced by another advisor by the supervisors.

Kasumi displays an unusual attraction towards the "Yellow Knife" and ends up letting herself be consumed by it, somehow coming to identify it with her beloved older brother.

In order to "protect" Kasumi by making sure nobody gets close to her, the "Yellow Knife" then starts projecting psychic waves that induce headaches in people unprotected by Borg symbiotes.

Sensing their desperation, Kumi's reconstruction is sped up by an unusual merging with her Borg, and she recovers just in time to save Yuri and Kasumi.

Following this incident, Yuri, uncomfortable with Kasumi's unusual behavior and Kumi's apparent return from the dead, wanders into the Forest of Spaceships, a dangerous area of the school inhabited by aliens, where she is attacked and separated from her Borg.

In the aftermath of the Sunflower invasion, the Tsubaki Class is treated for their injuries, with the students permitted to miss the Japanese entrance exam and pick any junior high school they wish.

Headmistress Okada points out to Ms. Hisakawa that it may be a good thing for the humans to be allowed to choose other clans or aliens they wished to fuse with.

Thinking she has put all alien-related matters behind her, Yuri is dismayed to find herself once again drafted as an alien fighter along with Kumi and Kasumi when a spaceship lands at Hinode.

The other alien fighters, along with Ms. Hisakawa who was sent by Principal Okada to investigate the reports of older generation Borg appearing at Hinode, arrive to rescue Yuri.

In May 2015, Kasumi enacts her plan, and a group of Yellow Knife aliens descend on the Hinode Junior High School.

Unwilling to sacrifice Yuri in order to save herself, Kumi begs Monami to kill her before her Borg takes over completely.

Yuri crawls out from the Yellow Knife's stomach, but by the time she reaches the containment cell, Kumi's Borg has already taken over and she starts to lash out in desperation in order to fuse.

The story ends with Kasumi and Ms. Hisakawa going to California along with Kumi in order to help her recover, while Yuri remains in Japan as a member of the Hinode Junior High Alien Fighters.

Kumi, along with Borgs carrying Kasumi and Yuri's personalities, embarks on the maiden voyage of the Star Seed as an "astro-navigator".

Kasumi's Borg-Yellow Knife hybrid onboard the now-crippled Star Seed combines its power with Yuri's Borg to send a signal back to Earth to inform the team.

However, the signal compels the Principal to "obey the originals" and she kills Kasumi, leaving two Borgs trapped in the Star Seed with no communications with Earth.

The anime was licensed and released in North America by Central Park Media, with the series being aired across the region on Comcast's Select On Demand service.

As the OVA series ends halfway through the story, the DVD was made available in America in an "Ultimate Edition", which included all three original volumes of the collected translated manga.

[14] Helen McCarthy in 500 Essential Anime Movies praises the OVA's pace and interesting character designs, stating that "although this looks at first like a cute, child-friendly sci-fi tale, it's actually a scare allegory on what it means to grow up".