Heart no Kuni no Alice - My Fanatic Rabbit

One day, a mysterious rabbit-eared man named Peter suddenly appears in Alice’s garden and kidnaps her, whisking her off to a dangerous world where every resident brandishes a weapon. Trapped in this land in the midst of a three-way power struggle, Alice accepts an offer to stay at the Hatter’s mansion. At the mansion, Alice meets the Hatter’s right-hand man, Elliot March, who is likable and charming and…also sports a pair of bunny ears! And yet, Alice cannot get over the fact that Elliot is actually a Mafia hitman, willing to kill people without hesitation…In this popular Wonderland manga, the March Hare has finally arrived!!
(Source: Yen Press)