The immortal that wants to die

zehen a immortal living in the 21 century roaming around the world looking for someone or something capable of killing him to put an end of his suffering . He later meets up with a girl Mai Hashimoto the fun and caring Japanese high school teenage girl with a little secret of her own form unlikely alliance with the grumpy zehen ,to fulfill there goals and deepest desires was zehen immortality just a curse placed on him or is there more that meets the eye to his immortality