According to CrazyJapanNews’s scan of a page from Tonari no Kaibutsu-kun’s 11th volume, manga Tonari no Kaibutsu-kun was announced to end in its 12th and final volume. The manga was serialized for a little over four years in Dessert shoujo magazine, and its anime adaptation aired last season. The volume will include the previously announced OVA.
Source: CrazyJapanNews