Kunikata Eita

"Sayu, no... It's been a while Katsuki."

The protagonist's childhood friend, he was at her side when she lost her memories.
He always played with Sayu and Minato when they were younger. He was bullied then because of his cute appearance and was protected by the tomboy Sayu.
Now that he's grown up he wants to become stronger to protect her instead, so he started training kendo in the dojo behind the Haruki Shrine with Touma as his teacher.
He also joined the kendo club at school and aims to become their ace, but because of his kendo infused lifestyle he isn't good at studying. However he's a bright and friendly guy who is the center of attention in class. He's pretty popular with the girls at school too, but he doesn't pay it much mind.
After being reunited with Sayu after her parents died, he wants to get their past relationship back, so he starts helping Ren with trying to find her memories.