I Think I Turned My Childhood Friend Into a Girl Vol. 2 (manga)

It's a familiar story: a popular high school student gives their plain friend a makeover and transforms their life. But this time, both the popular student and the plain friend are boys! Mido Kenshiro has loved cosmetics all his life, keeping his obsession a secret. But when his childhood friend Hiura lets Kenshiro practice applying makeup on him, the results are earth-shattering - for both of them.