He sold all his life soul to the grim reaper for 1 year.. And as u can see at the ticket there's 364 life soul.. I think he can use all ticket as long as within 1 year
His lifespan is not decreasing cuz first of all his death is set in first of the story that his life span is only 1 yr left and ge can do all he want to do in 1 yr even if he uses all his tiscket and first of all the girl is the key to his goal to find her mother afcourse he can risk a ticket to protect her tho okay
No only 100 ticket he can use but I think the ability of the soul that he use like bruce lee will remain in his body thats why he can use that anytime in one yr thats only I think but we will find out soon
is the mc still aware that everytime he ripped his card, his life is decreasing? cuz they still haven't find a single clue to his mother yet almost half of his life was wasted and his mind looks like on the girl only. Man, dont get attached, you will only live for a year, remember?