Boss Bride Days, Volume 2 (Boss Bride Days #3-5)

Sakura (a shut-in nerd) is favored by an old man (who is, unbelievably, a yakuza) she saved. The grandfather declares to his three grandsons that the one who wins her heart will be the next clan leader, and she begins to live with the three handsome brothers! As Sakura spends her exuberant and eventful days as the boss bride, sneaking into a JK cafe and being forced to participate in an illegal casino, she discovers the charms of these three brothers...?