Searching for Mangas with Romance-Ecchi combination, with really good Romance, so the Ecchi shouldn't be the Main Focus. No Harem pls, unless the MC will never even consider another girl (like in Ai Yori Aoshi).

Nana to Kaoru

Cant really assure that everything fits, I just filtered my reading list and picked some...
Koisome Momiji
Kagami no Kuni no Harisugawa
Kimi wa Midara na Boku no Joou - really really ecchi but at least romance as well... I liked it.
Yumekuri
Onna no Ko ga H na Manga Egaicha Dame desu ka?
Sankarea
Juukinzoku Kanojo - more rom-com then serious romance though but really liked the characters.

Itoshi no Kana
Velvet Kiss
Change 123 (bit of action tho)
Hetakoi
Kanojo wa Sore o Gaman Dekinai
Koibana Onsen
Oretama
Sore wa Totsuzen, Unmei no Aite ga

These are some of the ecchiest. All are completed.

Haru yo koi completed, slightly harem? It's more of a guy's life and romances, but it does have a complete ending with one girl.

Love lucky once again more ecchi, but this one is devoted to one guy and his love to an idol. Has a complete ending but is quite predictable, which is partially why it's good too I guess.

Quote from Ryan POTLOT

Nana to Kaoru

Yes. The best IMO. The ecchi moments are there simply to act as a conduit between the two, who otherwise wouldn't spend much time together and I don't even really consider it as ecchi anymore. It's not like Koibana Onsen where it seems like the story is filler between sex scenes.

I really like Sakura Sakura (Morishige) so far.

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