Hitotsu Yane no Shita no Kedamono
Complete | Kuroiwa Chihaya | 2013 released
Ato No Matsuri
Ongoing | MATSUMOTO Mitohi | 2000 released
This is a sequel. Read the prequel here: http://www.mangago.me/read-manga/classmate_no_josou_o_tetsudattara_kawai_sugite_furue_ga_tomaranai_ken/bt/145989/Ch5
Syrup [Bitter] Anthology