I've made it to Stg4 a couple times in Tumiki, but…

Never with no misses through the first two (I even had a weird case on the end of the first one, knocked off the first two parts at once so I had two high health spasm turrets blasting at me)

To no surprise, I got struck four times in the third stage. At least I got to almost get through that stage. Kento really saved on the bullet mutation until then