Event-D is a sci-fi visual novel that tells how a person explores the cosmos, and he questions the role of humanity in this endeavor. This is a kinetic visual novel. After many years of planning, the first manned mission to colonize the planet Mars is finally launched into space. But halfway through the mission ends in tragedy under mysterious and inexplicable circumstances. Claire, a candidate for command of a future mission to Mars, dreams of leaving Earth behind and starting a new life on Mars, but her dreams are crumbling when, due to the first mission tragedy, all other colonization missions are postponed indefinitely.