Izumi Yamamoto is a female character from the visual novel and anime series Grisaia: Phantom Trigger. Visually, she is recognizable by her orange hair, which is cut short to her ears, and her purple eyes. She is a supporting character in the narrative.

Her primary role at Mihama Academy is that of a gunsmith. She is a student belonging to the 2nd year Mechanical Engineering class. Izumi specializes in working with metals and resin, and she is responsible for the maintenance and repair of nearly all the guns and ammunition used by the other students at the school. Her technical skill is so advanced that by examining the wear and tear on a weapon she is servicing, she can discern not only how the gun has been used but also infer the physical condition of the shooter who wielded it. A distinctive detail of her work is that every time she services a firearm, she updates a QR code seal attached to it.

When not working in her role as a gunsmith, Izumi has a habit of listening to lively, clattering music at high volume through her headphones. She becomes deeply absorbed in this music, to the point of entering a trance-like state while enthusiastically playing air guitar. The information available does not provide specific details regarding her deeper personality traits, personal motivations, key relationships with other characters, any character development she may undergo, or her background before coming to Mihama Academy.