Akira Kagetsuki is a high school student who moved to Kaminohara from Sendai, driven by a desire for vengeance after his sister was injured in a Monster Strike battle. This incident fuels his initial actions and demeanor. He typically maintains a cold, calculating exterior but displays moments of unexpected kindness, such as offering directions to a lost Haruma Kagutsuchi. In Monster Strike battles, he employs intense violence and strategic precision, utilizing the ability to read enemy attacks—a defining trait noted by Haruma.

Recognizing Akira's potential, Haruma Kagutsuchi proposes recruiting him for his team with Aoi Mizusawa and Minami Wakaba. Despite initial reluctance from Aoi and Minami, they agree based on Haruma's judgment, as he had reserved the fourth team member spot for someone with Akira's capabilities. The team undertakes "Operation Recruit Akira" to persuade him to join. Akira's character design includes glasses and a birthmark or mole. Beyond "Rain of Memories," he appears in multiple Monster Strike narratives: the main anime series, "Mermaid Rhapsody," the film "Monster Strike The Movie: Hajimari no Basho e," the special "Zoku Saishū-banashi - Pandora no Hako," and later seasons and films including "Kieyuku Uchū-hen" and "Sora no Kanata."