Jinmon Yuugi

Main hero who is an amateur detective is invited to drink in the bar with a beautiful woman while on a voyage. They move to her room and... the next thing he remembers is her dead body on the floor. Hero is the main suspect, but famous British detective agrees to allow him freedom of movement till the end of voyage as an opportunity to search for a different culprit. Time is limited and hero will have to use all his wits and interrogation skills to get to the truth.

[From vndbreview]