I am Worried that my Childhood Friend is too Cute!

Synopsis

For the first time in 10 years, Amano returns to the city he lived in as a child. On his first day of school he runs into his childhood friend, Yukio Sawatari, when suddenly he (a male friend) turns female! As it happens, Yukio has a rare medical condition called "spontaneous isomerism metamorphosis", commonly known as "sudden sex change syndrome", causing him to... well, you can probably imagine what. The female childhood friend ♂ is so cute it's frustrating!! A romantic comedy full of forbidden TSF love! (Source: Kadokawa, translated and edited)