The Kamen Rider Who Alchemizes in the Manga

"Tian Xingjun, you played the guitar wrong." Duanmu Tianxing, a seemingly ordinary high school student, received a mysterious metal card one day. At the same time, his two childhood sweethearts, the energetic fool Yui Hirasawa and the socially fearful guitarist Goto Kazuri, seemed to be involved in some kind of unusual incident. Weird "sonic monsters" began to appear on campus, devouring music and distorting melodies, and strange note marks appeared on Yui and Yili... When Tianxing put on the belt and transformed into Kamen Rider Gothard, he discovered that the outcome of this battle was actually closely related to the girls' music? "Our daily lives are guarded by ourselves!" ... "Hey, Xiaoxing, after today's practice... Can you accompany me to eat crepes?" "T-Tian Xingjun... I-I will work hard..." ... "Transform!" "Today's BGM will be played by us!"