he comes in handy for a lot of ninja exams also so its like an investment that keeps paying itself back. Since if u can get a couple more magatama per day itll pay itself back pretty quick. like if u beat a couple more ninja exams and get yourself an extra 2 lvl 2 magatamas per day that is 24 coupons worth right there, then in ninetails u rank a bit higher fromt the damage boost earning yourself 5 more coupons per ninetails and an extra 50-100k coins thats around 10 coupons worth at least, so we are at around 34 coupons earned a day from owning iruka. Which amounts to iruka returning the 1k back to you in a month.