Psycho Mystery Series 'Three - Mitsu no Kioku'

When he regained consciousness, he saw his girlfriend, Miki, lying in a pool of blood. In the confusion, bloodstained knife slips from his hand. A hazy memory whispers in his head: "Did I... stab her...?" The protagonist, Seta Hideaki, is a second-year student at Higashi Second High School. Last month, encouraged by his few friends, Takashi confessed his feelings to Miki and they began dating. Just then, he develops short-term memory deficit disorder, a condition that impairs one's ability to remember recent information. Hideaki can only remember up to three events, such as conversations with people or information he has seen. Relying on these faint memories, he retraces the events of that night and begins to approach the crime he committed. [Translated from G-Mode official page]