Just search YouTube for kakuzu grudge breakthrough, you will find them. I heard the same screams when Shisui came out, and when edo hiruzen came out. Truth is the whales that kill you in 1 round with edo hiruzen will still kill you in 1 round with grudge breakthrough. But, don't expect his breakthroughs any time soon. Once the whales get him, then they will stop spending on any other ninjas they release. Grudge frags go for just under 200 coupons each. So, 100 frags to get to 4* is ~20k coupons. Plus another ~10-20k coupons for each book.