In a Tokyo in the not too distant future a young girl studies deligently with ambitions of soon attending space academy. If things work out just right, her future may very well be among the stars as well. And yet, every time she looks up to the stars there is a sense of melancholy in her heart. A sadness surrounds Asumi, as space exploration itself has profoundly impacted her life for as long as she can remember. But she is not alone...A young man wearing a lion's mask is always beside her. He speaks of the constellations and galaxies as if he they were like home. He knows what it is like to love the stars—slightly bitter and yet always so warm and inviting. Truth is he has gone through much of Asumi is just experiencing. And now in spirit he will forever be with Asumi guiding her on her path to space.

Where were you when the first International Space Station was scrapped and dropped into Earth's atmosphere? It was Asumi's first day in space school, and she promised Lion she would not cry or be homesick as she will be leaving her quiet seaside town for the big city. Waiting for her in Tokyo will be a lot of work. She is going to have to go through the rigors of space exploration training at the Tokyo Space School. After hours, Asumi will focus her efforts on homework, when not earning her tuition at the neighborhood Denny's. It is not unccomon to run 20 laps around the campus each day. Follow that up with physics and advance mathematics courses in the classroom. Only to close the night by mapping out the constellations in the southern sky. This is just what she expected the TSS to be, and yet why is it so hard to invision going to space someday? With all of the work she and her classmates are efforting, why does space still feel so far away?

Asumi is going through her growing pains right now. She knew this new challenge would not be simple. Mentally and, even with her petite frame, physcially she was prepared for almost anything the Japanese Aerospace Exploration Agency (JAXA) could throw at her. Emotionally, however, she was light-years away from being able to even take more than a few attacks on her long suppressed past. So when Asumi is at her lowest, a longtime friend, of the invisible sort, pays a visit. As he is grappling with his own past, she realizes that there is no way she cannot move forward. Nothing here can keep her from taking off!

Asumi is now in her second term at the Tokyo Space School. After struggling to be accepted into this elite program and some hardships once she was admitted, she quickly found herself developing her skills and her character through the many trials the school administered. Despite her diminutive size, Asumi has a huge heart and equally powerful drive and she will not accept failure as an option. So when she is confronted by protesters demonstrating against Japan's space program, she is torn by the memories of her past, which include her deceased mother, and the dreams she is working so hard to attain.

A group of high school students embark on space travel at the Tokyo Space Academy, showing how humanity can thrive through advances in science and technology.

Asumi's latest and most challenging flight simulation trial continues. She along with her classmates have been put into small escape pods, the actual pods that the International Space Station currently uses, to simulate traveling through space and an atmosphere re-entry. The pods are then covered and transported into the Japanese wilderness where after some rough handling and a designated allotment of time the pods automatically open up leaving the students disorientated and desperate to find civilization.

Asumi, Kei, Marika, Fuchuya, dan Shu pergi ke Yuigahama untuk liburan musim panas. Untuk mendekatkan diri, mereka pun bertaruh dan siapa yang kalah harus menceritakan rahasia pribadinya. Namun, Marika yang kalah malah menolak untuk bercerita. Belakangan, terungkap bahwa Marika adalah seorang manusia kloning. Editor's Note Drama, Sci-fi, Slice Of Life, Supernatural.

突然始まった校外での訓練に戸惑うアスミたち。それは昔監獄だった場所に入れられ、そこから脱出するというものだった――。

In the ninth volume of Twin Spica, Asumi and her classmates are getting closer and closer towards graduation, and changes in store for this group of friends. There will be good-byes to be said and that might end up causing some tension within this group. Some of that friction might be spurred on from outside of the Tokyo Space School as the media has caught on to the identities of at least one prime candidate.

新学期になり、3年生に進級したアスミたち。宇宙飛行士選抜試験を受けた秋をはじめ、バイトを始めたマリカ、後輩ができて先輩らしくしようとするアスミなど、みんなが最後になるかもしれない宇宙学校での1年をがんばろうとしています。そんな時、やめたはずの佐野先生が学校にやってきた。獅子号事故について調べていた佐野先生はある事実を突き止め、そのことを確かめようとするのだが……。