From birth, Cesare Borgia is surrounded by hellish shadows that threaten to consume him. Damned by his own father, hated by his closest brother, separated from the sister who loves him, and driven by the demons of Hell itself, he sets out on a quest for power that threatens to set the world of Renaissance Italy ablaze. Will he find salvation in Michelotto, a mysterious assassin bent on saving Cesare's soul -- even if it means slaying his demon-possessed body? Or will all Italy be seduced by the tragic eyes of the infamous murderer known as Cesare Borgia?
(Source: Go! Comi)

Tsubasa has always been a little weird and detached, but when he gets dragged into a different world to rescue his supposedly lost mother, his brother Tokimaru knows that there is something more to his background. There they meet up with a mysterious character Shroud, captain of a pirate's ship, and he becomes an aid in their adventures. This is a very mild shounen ai series, but the story is very strong with lots of action, and all the characters are very memorable.

from Fantasy Shrine:]
Blessed with looks and brains, Tsubasa is cool with everyone except the devil-may-care Tokimaru, whom he refuses to open his heart to, in fear of Tokimaru's safety. As fate would have it, they are both dragged into another dimension when an unknown entity attacks them and tries to snatch the "secret" from Tsubasa. For 2 months, these two venture in the wonderland where pirates and wizards roam! What in the world is the "secret"? And who is the blond pirate, Silver, who seems to be helping them?

Shin and Leona are childhood friends – she has always been fascinated with the mysteries of the ancient Near East, and he has always been fascinated with her, to the point where he is ready to follow her thousands of years in the past, to the days of the Kingdom of Babylonia, where she has a very special part to play…
(Source: Aerandria Scans)

When an ancient being is freed by an innocent girl, he offers to grant her heart's desire -- but Seto is bound to bring misery and misfortune to whoever releases him from his prison. Seto's help in winning Marie's true love dooms her to a dark fate...but has the demon unwittingly doomed himself, as well?