Circle.

Japanese name: 介錯 (Kaishaku)
Members: 七戸輝正 (Shichinohe Terumasa) and 太田仁 (Ota Hitoshi)
Pixiv username: seven

Kaishaku is a two-member mangaka circle, most famous for their Kannazuki no Miko creation. The circle name comes from Kaishakunin, an appointed second person whose duty is to decapitate one who commits seppuku.