Hanarai

Tenma Madoka is the soon-to-be proprietor of his family's fireworks workshop, “Mantan ya”. At his grandfather’s retirement party, a handsome young man named Kikusawa Mitsuki pops up and claims to be grandpa's ex-lover!

Chapters 1-4 - Hanarai
Chapter 5 - A Thousand Hanarai
Chapter 6 - A New Story
Chapter 6.5 - Omake