✔ 最佳答案
That would definitely be KashiMashi: Girl Meets Girl
It is both manga and anime, but you would want to see both, as things are handled differently, as it is a short-run manga (5) and a one-season anime (12, with an OVA).
The basic plot isa young high school boy named Hazumu Osaragi declares his love to classmate and close friend Yasuna Kamiizumi, but she quickly rejects him. Dejected, Hazumu climbs Mt. Kashima and is killed when an alien spacecraft accidentally crash lands on him.
To rectify this, the alien in the ship named Hitoshi Sora brings Hazumu back to life, but inadvertently regenerates him as a female right down to the DNA level.
Yasuna, a rather feminine girl, has a unique affliction which makes her incapable of seeing males, and instead sees males as covered in a gray, hazy blur. Hazumu's childhood friend Tomari Kurusu, an athletic girl and tomboy, finds Hazumu's change difficult to cope with. Tomari starts to realize her own romantic feelings for Hazumu as Yasuna starts becoming closer to Hazumu.
Will this work for you?