Solo single from Koichi Domoto comes in three varieties: two limited editions with different bonus DVDs and one regular edition that features one bonus track. All songs written by Domoto himself. "Deep in your heart" is the theme song to anime series "Juousei" starring Koichi Domoto and "+MILLION but -LOVE" features as opening theme to TV show "Ongaku Senshi MUSIC FIGHTER." Regular edition includes 2-fold, 4-page booklet, the two main singles and bonus song "UNBREAKABLE" which is not included on limited editions A or B.