Yatamomo
A rare happy ending. Part of a serious: 1) Yatamomo (2014) 3 volumes http://www.mangago.me/read-manga/yatamomo/ 1.5) Sumomo (2015) [Prequel] http://www.mangago.me/read-manga/sumomo_harada/ "Hashiyasume" is a crossover with Yoru to Asa no Uta 1) Yoru to Asa no Uta (2015) http://www.mangago.me/read-manga/yoru_to_asa_no_uta/ 1.1 Aru Otoko no Uta (prequel) http://www.mangago.me/read-manga/aru_otoko_no_uta/ 1.2 Aru Otoko no Higeki (2016) - what happened to Asaichi http://www.mangago.me/read-manga/aru_otoko_no_higeki/
Sugar Pain
Part of a series: 1) Sugar Pain http://www.mangago.me/read-manga/sugar_pain/ 2) Bitter Pain http://www.mangago.me/read-manga/bitter_pain/
Kanashii Kotoba
Part of a series: Direct Sequels: Vol 1. - Ashita, Ano Bed de. (2008) http://www.mangago.me/read-manga/ashita_kare_no_bed_de/ Vol 2. - Nemurenai Koibito (2008) http://www.mangago.me/read-manga/nemurenai_koibito/ Vol 3. - Kusuriyubi ga Shitteru (2008) https://www.mangaupdates.com/series.html?id=36886 Vol 4. - Mou Kimi o Matanai (2009) http://www.mangago.me/read-manga/mou_kimi_o_matanai/ Vol 5. - Chiduka-san ni Tsutaete (2010) https://www.mangaupdates.com/series.html?id=58500 Spinoffs: 1) Nemurenai Koibito (2008) http://www.mangago.me/read-manga/nemurenai_koibito/ 2) Kanashii (Itoshi) Kotoba (2007) http://www.mangago.me/read-manga/kanashii_kotoba/ 3) Itoshi no Doctor Coat (2011) https://www.mangaupdates.com/series.html?id=64552
The Trigger
You'll hate Mitsui until you see his backstory with the sensei and then everything suddenly makes sense.
Makkurayami De Kimi To