17 Sai ~My Dear Angel~

Main character is a hard-working and prosperous businessman. Out of curiosity he joins "Angel Family" initiative to help lonely children. He pays for Fumika study and gives her consultation when required. However, he suddenly dies from overwork. God pities on his soul and decides to reincarnate protagonist as a young man till Fumika can firmly stand on her feet in life. So he ends up supervising Fumika study managing her daily routine.

[From vndbreview]