Ongekishin

Ongekishin (音撃震): Guitar-Oni attache Ongekishin to their Ongekigen to turn it into a guitar for their Ongeki Zan finishers. When not in use, it is usually lodged into the Oni belt buckle.

Todoroki
Ongekishin - Raigou (音撃震・雷轟): A

device on Todoroki belt. Todoroki attaches this to his Ongekigen Retsurai to turn it into a guitar for his Ongeki Zan Raiden Gekishin. At first, it has yellow chords (when it is owned by Zanki). Then, Ongekigen Retsurai is given to Todoroki, Raigou has red chords.

Zanki
Ongekishin - Zantetsu (音撃震・斬撤): Zanki attaches this to his Ongekishingen - Retsuzan to turn it into a guitar for his Ongeki Zan Raiden Zanshin. When not in use, it is usually lodged into the Oni belt buckle. It has yellow chords and red Oni's symbol.

Sabaki
Ongekishin - Gokuraku (音撃震・極楽): A guitar buckle. Sabaki attaches this to his Ongekigen - Enma to turn it into a guitar form for his Ongeki Zan: Enma Sabaki. It has yellow chords.