He loves seeing his smile.
Noya's always been like that: cheerful. No matter what anyone said, he's reliable, and definitely a great friend. Sugawara would know, they've been friends since childhood.
He didn't change much through the years - he grew up and matured of course, but he's always been friendly, cheery, funny and loyal.
But most of all, he smiles a lot. Anytime Suga felt down, anytime there was something to cloud his thoughts, Noya would make a joke and smile. It was like seeing the sun after a storm.
He loves seeing his smile.
It captured Noya's heart since the first time he saw it.
They were young, but while growing up, Suga didn't change. He was always sweet, kind, caring, and everytime he showed concern for Noya, he felt his heart pound in his chest.
But what he loved most was his smile. Whenever he tried to hide his frustration, his smile let him know that he'd always be by his side, and that he'd always be able to rely on him. It seemed to be able to heal all wounds.
They love smiling.
After all, if one of them smiled, the other would do so too, and they would both be able to see the smile they love so much.