Never
"You've never kissed a girl?"
"I- I- I- I- I-" Kazuki's face flamed. "I've never- girls don't- I haven't-" he stammered, face flushing madly.
Kahoko's face was red as well, flustered. "It's no big deal, really- I was just asking- I was only curious-"
"W-Why?" he asked, still embarrassed. "I- I mean- have you...?"
Kahoko blushed brilliantly, shaking her head emphatically in denial. Kazuki stared.
"Kaho-chan... you've... never been kissed?"
"Well, it's not like I've ever had a boyfriend," she said, defensive, her face a bright pink. "And- well- you don't just go around kissing people you don't like- you haven't either, Hihara-senpai, and you're a year ahead of me-"
"Kaho-chan has never been kissed?" The idea seemed to stun him, words registering on deaf ears as Kahoko continued on.
"And it's not like I'll never be kissed, I still have plenty of time-"
"Kaho-chan..."
Kazuki moved in front of her, meeting her eyes, her own looking up at him widely, before he tentatively pressed his lips to hers.
He could feel her breath catch, his heart thudding painfully, wondering if this was a mistake, if this was wrong, before she slowly closed her eyes, kissing him back gently, a soft hand coming to rest on his chest.