I wouldn't advise spending primarily into boxes for a CHANCE of getting Minato. I will say that I have gotten both Tendo and Hashirama in the same week from the boxes but I will chalk that up to pure luck. To add, I wasn't going for them specifically, I believe I was finishing up Hanzo . Personally, I say, if you want a full proof chance to get minato stack more coupons, and buy him straight out.