An fairly loose OVA adaptation of it exists, which focus's mainly on the main events between Gohda and Akane.
The game starts off with the protagonist, Gohda Jouji losing a baseball game that was either part of, or leading to Koushien. In an effort to lead a team to victory at Koshien, he transfers to Hakuryou. However, being that Gohda is more of an idiot than the 3 idiots combined, he doesn't realize that he'll never have a chance at going to Koshien again as he's a third year student.
Anyway, he falls in love with Suzumiya Akane upon his first sight of her. He tries to do various things to curry her favor, supported by Kouzuki Yuuko, because he entertains her, and along the way meeting Yoroi Mikoto, who he proclaims to be the Messenger of Gaia. However because Akane is a bit of a bitch because of KimiNozo, and Gohda is really dumb, these actions end up making her grow to dislike him.Eventually, after joining a committee for the "White Autumn" festival, where he meets Sakaki Chizuru, and suggesting they scrap it for an Akane Festival, Gohda is eventually transferred to Class 3-B, the class of Jinguuji Marimo. Here he meets the some of the main cast of Muv-Luv, such as Tamase Miki and Ayamine Kei. Eventually the White Autumn Festival happens, and Akane asks to meet him at the Tree behind Hakuryou. Here she relates to him a short version of the events of KimiNozo from her perspective, and admits that she had grown to like him, however because she wasn't sure if that was because she was seeing 1998 Takayuki in him or not, she denies his feelings, and apologizes to him.
This leads to Gohda breaking down and crying at the base of the tree until the next day when he's stumbled upon by Kagami Sumika, who is looking for one Shirogane Takeru. She gives Gohda a handkerchief to dry his tears. Gohda is so utterly moved by this act of kindness that he beings to to fall in love with her. However, these feelings are cut short by the entrance of Shirogane Takeru, whose existence's very nature denies his feelings and that's the last we see of Gohda, as he had transferred to another school somewhere, by the time the next school day arrives, as shown in Muv-Luv
Alternatively for the True Route, during the White Autumn Festival, if Gohda chooses to talk deeply with the Gym Teacher, Umeda, of whose existence Gohda had uncovered the truth of, Gohda is forced to become the Space Knight, Tekkumen and defend the Earth from aliens who wish to destroy it, after various events happen, such as Gohda's former classmate Haseo turning into a robot.
There are also multiple bad ends spread through out the game that occur if Gohda pressures Umeda too early on.
Haseo: Member of Class 3-D
Umeda: Gym teacher at Hakuryou
Shirogane Takeru: Love Nucleus, whose very existence is enough to mercillessly crush the budding feelings of love others may have towards those attracted to him.