From "Teenage Mutant Ninja Turtles: Tale of Master Yoshi (#4.22)"
Honor. Integrity. Bushido. These were the ideals that drove Master Splinter's beloved master, Hamato Yoshi. He had traveled far to reach this castle fortress only to find four Foot elite warriors barring his way. But four or four hundred, it mattered not. For on this particular night, Yoshi was driven by a powerful force unfamiliar to him: hatred. Hatred that burned so bright it threatened to destroy him. Hatred born out of the need for revenge.