For someone so monotone and unemotional, it shocked everyone that he was dating someone with big eyes and a cute look. That blinding light in your eyes and bright smile was the reason why he randomly gave you little gifts.
He was addicted to making you happy and being in the warmth you provided.
After work, he found himself playing at his desk like usual to destress, focused on beating the final boss, when he heard a distinct squeal of happiness that he knew could only come from you.
You must have seen the little plushie he got for you, the one he made a special stop to after work to see you happy.
So, what if your bed was already filled with mountains of stuffed animals that consumed his body every time he slept? Hirotaka would deal with it to see that smile.