Tengu ss a Mini-boss in the second level of asian town. Background
Stay locked on Tengu at all times! He pulls the usual ninja tricks, jumping around and slashing and the like, but he can also duplicate. And all those duplicates will pull the usual ninja tricks in stereo. This is why you want to stay locked on: Jack is smart enough to know which is the real Tengu as long as he had a bead on the original. If you did not lock on, you will have to slice through the duplicates until you find the real one. You'll know you've found him when the duplicates disappear. Duplication is Tengu's only real dangerous trick, and since we've seen through it, he is rendered nearly powerless in front of Jack. In fact, the spear makes super short work of him, and I imagine a chainsaw is no different. It's easier to take care of him if you've destroyed the white walls because they would just get in the way otherwise; they also reveal a Rose Bush outer wall, which might come in handy.
You can also use the lamp posts around the area to soften Tengu up nicely. It seems he'll be stunned for a short amount of time after you slash him to get rid of his duplicates; this would be a good time to impale him or stick something in his head. Do enough damage and Jack can take his blades to take his head in a unique finishing move.
Using the Katana is a good choice due to its power & quick recovery between attacks, he will barely avoid it or will simply be stunned.
Quote: "You are no match for me!"
After you beat him, you get a happy onion. Yay.