SixTONES will perform the theme song for the upcoming drama 'Kokuhaku: 25-nenme no Himitsu,' starring Hokuto Matsumura.

Premiering on July 11, the romantic suspense drama follows Sota Yukimura, a man who has remained in love with the same woman for 25 years, blurring the line between devotion and obsession. Sae Okazaki stars as the heroine, Mariko Nose.

The theme song "My Only" is a heartfelt love song written and composed by idom and arranged by Naoki Itai. SixTONES performed it for the first time on the July 4 broadcast of 'THE MUSIC DAY 2026.'

Matsumura commented, "The song reinterprets the unique aspects of the story and its protagonist from a subjective point of view. It can be viewed as part of the same story or as a separate work, with each standing on its own while resonating with the other. Though mid-tempo, the song stands out for the strength of its emotions."