Fuyu no Hana

Fuyu no Hana (冬の花, lit. "Winter Flower") is a one-shot manga series by Sumomo Yumeka. It was serialized in Mugen Anthology Series.

Plot
The flower in Itadori will bloom in the summer, taking his life as it took his sister's but giving others longer lives, but how can he leave his childhood friend Rakka behind...?