In chapter 50, it cost's Aki 2-month's of his life span by touching angel devil's hand for a brief moment.

Let's assume that Aki only touches his hand for 3 second's, 3 second's of contacts cost 2 month's of the lifespans, so it will cost around a year of your total life spans just to be in psyhical contact with angel for 18 second's.

Average male life spans is around 72.75 worldwide, minus your current age.(average age of an anime fan is around 18-25 ) , which means you have around 47.75-54.75 year's of lifespan's to spare,

47.75*18 second's = 859.5 second's
859.5/60 = 14.325 minute's
54.75*18 second's = 985.5 second's
985.5/60 = 16.425 minutes

In conclusion, you get to pound that angel bussy for 14-16 minute's straight before losing your life,
Which is more than enough for me cause i wouldn't even last 10 second's in him.