Sobo To Boku Obaa-chan, Nanika Dechau Yoo The Motion Anime

During the night the protagonist wakes up. He felt something and that spooked our hero. It turns out that Shota spent the night right next to him. His body was touched and the hero felt weird. He started getting a boner and wasn't sure what to do. Eventually, decided to act upon the feelings. The animation is top-notch.