This is my absolute favorite from when I was growing up. I go back to read this so, so, so often. It's on the fantasy side of things. One of the tags is Shoujo.
http://www.mangago.zone/read-manga/kanata_kara/
How did you know underrated is my specialty? (⌐■_■)> lol jk These are some manga I feel are undermentioned around here Hope you enjoy any!
Yaoi:
http://www.mangago.zone/read-manga/shinjuku_lucky_hole/
http://www.mangago.zone/read-manga/coponicus_no_kokyuu/
http://www.mangago.zone/read-manga/arrested_man/ (some stories suck, but some are work of genius. Try Naive Gespent ;D)
http://www.mangago.zone/read-manga/ultras/
http://www.mangago.zone/read-manga/koi_no_tsubo/
http://www.mangago.zone/read-manga/anxiety_of_soul/
http://www.mangago.zone/read-manga/bannin/mf/v01/c004/
http://www.mangago.zone/recommend-manga/ludwig_ii/
http://www.mangago.zone/read-manga/metro_dog/
http://www.mangago.zone/read-manga/the_man_of_tango/
http://www.mangago.zone/read-manga/pink_takaguchi_satosumi/
http://www.mangago.zone/read-manga/sakende_yaruze/
http://www.mangago.zone/read-manga/vibrator_company/
http://www.mangago.zone/read-manga/maou_no_amai_keiyaku/
http://www.mangago.zone/read-manga/the_prince_of_happiness/
Shoujo (Okay, two are seinen, but they feel shoujo-ish):
http://www.mangago.zone/read-manga/miman_renai/
http://www.mangago.zone/read-manga/dokuhime/
http://www.mangago.zone/read-manga/dont_cry_girl/
http://www.mangago.zone/read-manga/koi_kaze/
http://www.mangago.zone/read-manga/please_save_my_earth/
maybe try these (if you haven't already):
http://www.mangago.zone/read-manga/sweet_bitter_candy/
http://www.mangago.zone/read-manga/tear_drop/
http://www.mangago.zone/read-manga/kimi_wo_mukaeni/
http://www.mangago.zone/read-manga/soredemo_yappari_kimi_ga_suki_fujimoto_haruki/
http://www.mangago.zone/read-manga/hibi_koikoi/
http://www.mangago.zone/read-manga/ringo_ni_hachimitsu/
http://www.mangago.zone/read-manga/kare_no_barairo_no_jinsei/ (sequel)
http://www.mangago.zone/read-manga/sore_wa_isshun_no_hikari_dewanaku/
http://www.mangago.zone/read-manga/open_air/
http://www.mangago.zone/read-manga/square_na_kankei/ (first story)
shoujo
http://www.mangago.zone/read-manga/kanata_kara/
yaoi:
http://www.mangago.zone/read-manga/castle_mango/
http://www.mangago.zone/read-manga/the_hinanomori/
http://www.mangago.zone/read-manga/jazz/
http://www.mangago.zone/read-manga/my_darling_is_english_gentleman/
http://www.mangago.zone/read-manga/home_drama/
http://www.mangago.zone/read-manga/cafe_latte_rhapsody/
Are there any underrated completed yaoi or shoujo mangas? let me know, thanks in advance :)