Ao no flag
Shimanami tasogare
Blue flag, goodnight punpun, Okaeri Alice, and Ganbare! Nakamura-kun!! are some of my suggestions. But I think blur flag might be your best bet
https://www.mangago.zone/read-manga/sangatsu_no_lion/
https://www.mangago.zone/read-manga/to_all_the_corners_of_the_world/
https://www.mangago.zone/read-manga/ikoku_nikki/
https://www.mangago.zone/read-manga/ao_no_flag/
https://www.mangago.zone/read-manga/smells_like_green_spirit/
https://www.mangago.zone/read-manga/kakukaku_shikajika/
https://www.mangago.zone/read-manga/ran_to_haiiro_no_sekai/
https://www.mangago.zone/read-manga/after_school_mate/
https://www.mangago.zone/read-manga/kono_setsugen_de_kimi_ga_zutto_waratte_irareru_you_ni/
https://www.mangago.zone/read-manga/kimi_to_uchuu_wo_aruku_tame_ni/
https://www.mangago.zone/read-manga/nana/
Coming of age recs, beautiful art and completed ones only. The more realistic and relateable it is, the better. ╮(￣▽￣)╭
(If u know any coming of age movies and shows with summer vibes, i'd like some recs too!!)