Nino Nakano is the second sister of the Nakano quintuplets. She usually acts as the mother of the family, she cooks for them and takes care of their medical needs. Among the five sisters, she is the one who has the highest hostility towards Fuutarou and often rebels against him.

She confesses to Fuutarou in chapter 59. Fuutarou does not hear it so she confessed again in chapter 60.
(Source: Gotoubun no Hanayome Wikia)