You file a support ticket, and select the spend credit option. You then need either
5 ads Change an already customized Kaho or Pussy Cat Bell into another existing customization
15 ads Change an already customized Kaho or Pussy Cat Bell into a non-existing customization
30 ads Change an uncustomized Kaho or Pussy Cat Bell into an existing customization
40 ads Change an uncustomized Kaho or Pussy Cat Bell into a non-existing customization
You say which sprite you would like in your ticket, and include "Yes, I am aware this kaho change will cost me X amounts of Ads."
For more info on support tickets, you can read
here.
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