You are my sunshine, my only sunshine...

Humming and singing, to their own surprise, had become an important thing in their relationship.

It had all started when they had just gotten together at the end of their first year in high school; after the disaster of getting locked into their locker room overnight.
Now, sometime after becoming a couple, Kageyama had to pick up all volleyballs in the gymnasium. By the time he was finally done, almost all others had already changed into their school uniforms, ready to go to class. Hinata was still toweling himself off from his shower, so Kageyama had the shower room all to himself. And, all by himself, he relaxed enough to hum.

He was humming a random tune and with each step in his shower routine, he hummed more loudly; forgetting the world around him for a moment.
Kageyama liked to hum, and to sing, and to trill - but just to himself, not in front of others. So, when Hinata suddenly heard humming from the shower room while he waited for his boyfriend, he was more than surprised.

Kageyama nearly shrieked when he walked out of the shower room still humming, but with Hinata sitting there staring at him.

„What- WHY ARE YOU STILL HERE, BOKE?!" he exclaimed in shock and embarrassment. He had never let anyone hear him hum or sing, and now Hinata of all people, his boyfriend, had heard.

„I was waiting for you to get changed so that we could walk to class together... But Kageyama, you-"

„Don't say it please. Just forget that it happened, and I'l never annoy you with my horrible humming again."

„What?! No! Tobio - that humming was beautiful!"

Kageyama didn't know what to say to that. He had expected Hinata to laugh at him or tease him or to just really say anything other that what he just said.
But Hinata was still looking at him with this honest awe in his eyes.

„You... you liked it?" he asked hesitantly. Water was dripping from his skin, his hair was a damp mess from showering, he had been caught humming for the first time and now, Hinata was looking at him as if he had just given him the world.

„I loved it," he breathed before he stood up and slowly walked up to Kageyama. Hinata gently cupped his wet cheeks with both hands, his eyes beaming.

„I loved it!" he exclaimed, bouncing on the heels of his feet in excitement. „I loved it, I loved it! It was so beautiful, it was like - I can't even find the words! Enchanting? Magical? Wait - are you secretly a mermaid or something? With how beautiful that was?" Hinata rambled. It made Kageyama blush furiously.

„You really liked it that much?" he breathed, his face and ears completely red.

„Yeah, I really liked it that much. I didn't even know that you were the type to sing under the shower. Well, hum in this case," Hinata giggled.

„I... I also sing. Sometimes. I only hummed because I didn't think that someone would hear it," Kageyama admitted.

„What? You also sing?! That's so awesome!" Hinata cheered. „Sing for me sometime! And hum for me sometime!" he asked with closed eyes and a fond smile.

„Okay. For you..." Kageyama gave in. He had been reluctant, but when Hinata opened his eyes and Kageyama saw pure love and fondness radiating in his gaze, all insecurities about this decision were blown away.

It still took him a while until he was comfortable with it, though. It wasn't as if he didn't trust Hinata - but he had never shared this part of himself before.

Humming and later on singing in the shower was the first step. It was always a gentle tune or a slow song, and Hinata beamed every time he heard one; and Kageyama got comfortable with the idea of letting Hinata hear him more with every time he allowed himself to show this part of himself. It took him a few weeks, but by then, he was humming without second thought when he was alone in the locker room with Hinata.