Natsuki Sakaki is a soft-spoken high school student and an intelligent-type idol under 315 Production, where he is a member of the idol unit High×Joker. Before becoming an idol, he played bass guitar in his school’s light music club alongside his childhood friend Jun Fuyumi and other future unit members. His quiet and shy nature makes him slow to speak, even around close friends, and he prefers to observe his surroundings rather than initiate conversation. He tends to stick close to Jun in unfamiliar situations. Despite his reserved demeanor, his presence as the unit’s bassist provides a steady foundation for High×Joker’s musical performances. His motivation for pursuing an idol career stems from his deep bond with his bandmates and a desire to grow beyond his timid personality. Key relationships include Jun Fuyumi, who acts as a protective anchor, and the other members of High×Joker—Hayato Akiyama, Haruna Wakazato, and Shiki Iseya—who gradually draw him out of his shell. Over time, Natsuki develops greater confidence in expressing himself and taking initiative, both on stage and in group interactions. His notable abilities lie in his bass guitar skills and his keen attention to detail, which allows him to support his unit effectively.