THE PORTOPIA SERIAL MURDER CASE

Kouzou Yamakawa, the president of the Loan and Savings Company, was found dead inside his mansion. Despite all the evidence indicating that it was a suicide, a detective (i.e. you) and his assistant arrive at the scene for further investigation.
The player must resolve the mystery of a murder by searching for clues, interacting with characters, and solving item-based puzzles.

[summary from Wikipedia and Japan Adventure Attack]