If you really want ninja.

Get Angel, around 16-17k should be enough, then get cloth from mission event to make it 20k.

- You would get tons of Seal Scrolls and Summon Scrolls from Lucky Stars.

- Chance of Masked Man and lots of Hashirama frags

- Mission Boxes, many goodies drop

- Chance of Tobirama and Sarutobi (funny enough I got Tobirama 2nd one with 200 boxes)

- Fukuromaru Deals

- 20k spent, Edo Roshi, many seal scrolls, charm boxes, and chimes for bonds.

Save your 7k for your Shisui, for next event. that should take you half way.

tbh get him thru lucky board is safer but it's up to you.