
Quick answer — the Rentarō Family performed 1 anime theme, including "Arigato, Daisuki ni Natte Kurete" from The 100 Girlfriends Who Really, Really, Really, Really, REALLY Love You Season 2.
the Rentarō Family performed the anime theme songs "Arigato, Daisuki ni Natte Kurete" (The 100 Girlfriends Who Really, Really, Really, Really, REALLY Love You Season 2).
the Rentarō Family's first listed anime theme is "Arigato, Daisuki ni Natte Kurete", the opening of The 100 Girlfriends Who Really, Really, Really, Really, REALLY Love You Season 2.