Anyone know a manga like black bird ?

in terms of drama and pacing http://www.mangago.me/read-manga/dengeki_daisy/ should be able to match. and both have age gap and capable adult guys as leading men too.
for fantasy, http://www.mangago.me/read-manga/the_bride_of_the_water_god/ is somewhat similar but this one's got way more amazing art than blackbird. and more drama too.

I classify this theme as Ecchi.
http://www.mangago.me/home/mangalist/73910/