Pls help me to find this manga

So I want to re read this manga but I forgot the title it is not yaoi more like a shounen ai but a lot of yaoish scene . The only thing that I remember is the MC was young boy and he was protected by a three adult guys from the enemy because the enemy considered the MC as a monster and sometime the Mc somehow become possesed and the MC become really strong. The three adult guy that protected him : one guy that are really close to the mc has long blond hair while the other guys is one samurai guy and the other one is a gun man . The last scene that I remember was all of them died because an army killed them and the made a promise to the mc that they will survive and live together something like that and I think there was continuation of this manga and on the second book of it all of them were reincarnated but they don't remember about their past life but they feel that they know or meet each other during the past. Then the art style of this manga is a little bit similar to princess yona drawing style. .
Pls help me and sorry for my bad english because I'm so desperate and it has also an anime version