Read the prequel 1st -
http://www.mangago.me/read-manga/gaten_na_aitsu/ (ch.4)
Spin off is another masterpiece -
http://www.mangago.me/read-manga/punch_up/
dapted from -
http://www.mangago.me/read-manga/yachin_hanbun_no_ibasho_desu/ (ch.4+5)
Chronological order of Pair no.3 KuonNanao's story STRICTLY. Read in this order -
http://www.mangago.me/read-manga/mujihi_na_otoko/
http://www.mangago.me/read-manga/mujihi_na_anata/
http://www.mangago.me/read-manga/mujihi_na_karada/
Chronological order of Pair no.2 ShinonomeYukimura's story STRICTLY. Read in this order -
http://www.mangago.me/read-manga/i_don_t_dislike_you/
http://www.mangago.me/read-manga/koi_ja_nai_kedo/
http://www.mangago.me/read-manga/kare_ja_nai_kedo/
http://www.mangago.me/read-manga/sunao_ja_nai_kedo/
http://www.mangago.me/read-manga/himitsu_ja_nai_kedo/
Chronological order of Pair no.1 MikadoTowa's story STRICTLY. Read in this order:
http://www.mangago.me/read-manga/i_want_to_be_naughty/
http://www.mangago.me/read-manga/warui_ko_demo_ii/
http://www.mangago.me/read-manga/warui_koto_bakkashite_gomennasai/
http://www.mangago.me/read-manga/warui_yatsu_demo_ii/
http://www.mangago.me/read-manga/warui_koibito_ja_dame/
http://www.mangago.me/read-manga/kare_ja_nai_kedo/ (ch.5 only)
http://www.mangago.me/read-manga/warui_ouji_demo_suki/
Datenshi ni Sasageru Uta