[just the fact that amami wanted to get him something is enough to warm him, even though he knows logically that of course he would; they're friends, and friends give each other gifts. subaru probably would've whined if he hadn't gotten anything, but not be seriously hurt by it -- he's not expecting anything in return for the things he gives others, after all, he just likes seeing the expressions on their faces and knowing that they're happy. or hopefully happy.

he draws the wires out, eyes lighting up at the shapes (childish as they would be to anyone else) and he sets them aside with care. next comes the clothes pins, which he seems more curious than anything about, and once they're both back into the safety of the backpack subaru'll tackle into amami's arms.

yes he knows you don't like it too much but he does not care he's huggy]

Ama-chan~! How dare you downplay yourself! You could've gotten me a bag of coins and I would've been happy, y'know?!

[food is love, so subaru won't downplay that, but for amami to consider this below that... please. the hug loosens after a moment and he'll let his friend go, picking up the backpack excitedly.]

You thought of me! You wanted to get me something! That's enough!