Undead-san no Bukiyou na Seishun

One day after summer break, Sana Tsukuyomi, a flawless young lady, returned to school as an undead. As a school health committee member, Hiyoshi ended up helping her navigate her daily life, despite her movements being as stiff as a corpse's... A school romantic comedy featuring a heroine who's both scary and cute! Source: Houbunsha, translated)