http://www.mangago.zone/read-manga/koimonogatari/
http://www.mangago.zone/read-manga/yamete_kudasai_mabushii_desu/ and the sequel.
http://www.mangago.zone/read-manga/koori_no_mamono_no_monogatari/
http://www.mangago.zone/read-manga/hidamari_ga_kikoeru/
http://www.mangago.zone/read-manga/doukyuusei_nakamura_asumiko/ and the sequels.
http://www.mangago.zone/read-manga/slow_starter_ichikawa_kei/
http://www.mangago.zone/read-manga/silver_diamond/
http://www.mangago.zone/read-manga/aitsu_no_daihonmei/
http://www.mangago.zone/read-manga/seven_days/
Oops it doesn't have a lot of chapters, but it's a cute slow buildup. <3
Do you know any good shonen ai manga with slow build and lot of chapters pleeeeeease , I love these (▰˘◡˘▰)