Homeless Tensei: Isekai De Jiyuu Sugiru Majutsu Jisoku Seikatsu summary:

Shinichi Tanaka used to be a representative director of a large company, but now he is homeless without money or family. On a rainy day he is struck by lightning and awakes in a strange place in the body of his younger self. What is the mysterious place he finds himself transmigrated into? A weird and turbulent adventure story of a 56-year-old man who reincarnates into a different world in his 25-year-old body!