Help plzz forgotton title

#1
He reincarnated to a family/clan then require them to keep traveling for safety reasons because of beasts roaming around the world .On his previous world, he is an assassin that got the knowledge of martial skills that he stole. He recognize his clan skill is in inferior one therefore he make an upgrade to it base on his previous life. he also teach a girl that failed to recognize as a warrior because she has water attributes while the clan is earth/or fire(dont remember) attributes. To power her up, he used his knowledge of his previous past to create techniques with water attributes and he is also require to do tattoos on her back also. Btw, because of this reason she has to marry him. Oh his martial art skills require him to eat hearts to power up. Chinese novel I think.