[It's a half-breathless, largely unintended reaction, one that slips out like he hasn't really realized he's done it — but if Kakyoin's intentionally going to use his prior knowledge to his advantage, it's not like he can really do much but accept and react to it in the best possible way.]
Maybe you're a kouhai who got held back a couple of years.
[To help ensure the recognition of that as teasing, he gives Kakyoin a little squeeze on "held", specifically for the double meaning.]
no subject
[It's a half-breathless, largely unintended reaction, one that slips out like he hasn't really realized he's done it — but if Kakyoin's intentionally going to use his prior knowledge to his advantage, it's not like he can really do much but accept and react to it in the best possible way.]
Maybe you're a kouhai who got held back a couple of years.
[To help ensure the recognition of that as teasing, he gives Kakyoin a little squeeze on "held", specifically for the double meaning.]