well he left out the part where she blackmail him to dating him so da-ae won't get inflicted, to da-ae herself so i understand she's being nice cus they dk she's shady
is this grandpa's way of putting yoshino in kirishima's care to train her inner badass out. by 'seducing' him, she gotta pull all her feisty personality to toughen her up since she's a person that lives among the yakuza