One-shots:
https://www.mangago.zone/read-manga/the_frontier/
https://www.mangago.zone/read-manga/will_we_live_happily_ever_after/
https://www.mangago.zone/read-manga/lit_a_light/
https://www.mangago.zone/read-manga/satou_san_is_on_the_left/
https://www.mangago.zone/read-manga/5_seconds_before_a_witch_falls_in_love/ (SEQUEL: https://www.mangago.zone/read-manga/5_seconds_before_falling_in_love_with_a_witch/)
https://www.mangago.zone/read-manga/a_goldfish_s_love/
https://www.mangago.zone/read-manga/drift/
More than 1, less than 5 chapters:
https://www.mangago.zone/read-manga/us_right_now/
https://www.mangago.zone/read-manga/you_are_my_angela/
https://www.mangago.zone/read-manga/ada_and_eyva/
https://www.mangago.zone/read-manga/club_katoto_chan/
https://www.mangago.zone/read-manga/i_decided_to_fake_a_marriage_with_my_junior_to_shut_my_parents_up/
https://www.mangago.zone/read-manga/umi_to_anata_to_taiyou_to/
5-10 chapters:
https://www.mangago.zone/read-manga/yoiko_no_shouzou/
https://www.mangago.zone/read-manga/love_me_like_i_do/
https://www.mangago.zone/read-manga/summer_lemon_and_overlay/
https://www.mangago.zone/read-manga/eat_u_up/
https://www.mangago.zone/read-manga/gentle_flutters/
https://www.mangago.zone/read-manga/love_countdown/
10-15 chapters:
https://www.mangago.zone/read-manga/handsome_girl_and_sheltered_girl/
https://www.mangago.zone/read-manga/45_seconds/
https://www.mangago.zone/read-manga/scarlet_yuino_chiri/
https://www.mangago.zone/read-manga/model_and_quiet_manager/
https://www.mangago.zone/read-manga/my_girlfriend_is_a_gamer/
https://www.mangago.zone/read-manga/yuki_and_the_authoress/
https://www.mangago.zone/read-manga/glass_flower/
https://www.mangago.zone/read-manga/composing_spring_in_this_room_where_cherry_blossoms_bloom/
https://www.mangago.zone/read-manga/mi_chan_to_airi/
15-20 chapters:
https://www.mangago.zone/read-manga/sadistic_beauty_side_story/
https://www.mangago.zone/read-manga/crescent_moon_and_doughnuts/
https://www.mangago.zone/read-manga/gunbured_x_sisters/
https://www.mangago.zone/read-manga/accept_my_fist_of_love/
https://www.mangago.zone/read-manga/run_away_with_me_girl/
https://www.mangago.zone/read-manga/sayonara_rose_garden/
https://www.mangago.zone/read-manga/tsukarekitta_onna_ga_shinuhodo_iyasareru_tame_ni/
https://www.mangago.zone/read-manga/the_flower_princess_of_sylph/
https://www.mangago.zone/read-manga/throw_away_the_suit_together/
One Shot/anthology/30 or less chapters (short stories). They must be adults. Thank you in advance!^^