Senpai, Who Are You Giving Your Second Button To?

"My second button? Sorry, it's already reserved." On graduation day, what awaited you, running up to your admired Naruse-senpai, was a mischievous smile and teasing words. Are you really going to give it to someone else...? To you who won't back down, the true feelings and sweet possessiveness the senior had hidden spill out —