18+ Shikisaki Shimai wa Abakaretai

One day, Tarou Yamada, who runs a detective business, slips on a banana peel and is reincarnated as Tsukushi Shikisaki, who is the younger brother of three beautiful sisters and who died on the same day. He ends up spending his time surrounded by three beautiful sisters, but he realizes that Tsukushi Shikizaki was killed by one of his three sisters...?!

(Source: Shueisha, translated)