Seshuusei Triangle

Koutarou Fujiki and his best friend Kajiwara once had a strange love triangle over Fuyuko. However, that relationship ended abruptly when Kajiwara left without any notice. Why did Kajiwara disappear? Does Fuyuko, now his wife, really love him? Koutarou is still suffering in his middle age, but an unexpected encounter in his hometown brings him back to his youth.

(Source: Kadokawa, translated)