What doesn't matter? Your little stomach ache, 'cause it's not the big thing making you hit your head against the door? Or the big thing, 'cause you wanna shrug it off?

[ leo says all that rather genuinely, his questions emphasized with the smallest tilt of the head.

and because osomatsu is someone he just met, of course he keeps on going: ]

If both things are bothering you, both things matter. There's not a lot of things in this world that don't matter, actually. I'd even say there's... no things in this world that don't matter! [ ... ] Did I say that right? Double negatives twist me up sometimes!