Tsubasa Kashiwagi, a former airline pilot, shifted careers to become an idol after being scouted by 315 Productions. The loss of his pilot job due to a professional error left him hesitant about new endeavors. His recruitment followed witnessing a Jupiter concert, where a producer's question about experiencing the "view from the stage" inspired him to join the agency.

He exhibits a gentle and friendly personality, frequently acting as a peacemaker within his idol unit DRAMATIC STARS, especially during conflicts between members Teru Tendo and Kaoru Sakuraba. Despite his amiable nature, he feels self-conscious about his larger physique. His appetite is notably substantial, allowing him to finish full meals in roughly five minutes. He has expressed future interest in working as a gourmet reporter and suggested collaborating with Teru on a cooking show.

While preparing for DRAMATIC STARS' debut live performance, memories of his piloting failure surged back, causing significant anxiety and nearly prompting him to quit idol work. Teru and Kaoru intervened, taking him to an airport runway fence—a meaningful location—to discuss his fears. This conversation helped him recommit to being an idol, drawing a parallel between the sparkling lights of an audience and the aerial views he cherished as a pilot. He subsequently performed with renewed confidence, overcoming his trauma.

Beyond the main series, he appears with DRAMATIC STARS as a rival unit in *THE iDOLM@STER Starlit Season*. He also features in a crossover event within *Granblue Fantasy* alongside Teru and Kaoru as playable characters.