Quick answer — "Arigato, Daisuki ni Natte Kurete" by the Rentarō Family is the opening theme of The 100 Girlfriends Who Really, Really, Really, Really, REALLY Love You Season 2.
"Arigato, Daisuki ni Natte Kurete" by the Rentarō Family is the opening theme of The 100 Girlfriends Who Really, Really, Really, Really, REALLY Love You Season 2.
"Arigato, Daisuki ni Natte Kurete" is performed by the Rentarō Family.