Kamaitachi (カマイタチ , Literally meaning "Sickle Weasel") is a technique created by Marshall D. Nicolas in an effort to make better use of his devil fruit's ability. This devil fruit allows Nicolas to become immune to any attacks that he can't see or react too, what Nicolas thought is, rather then letting his fruit's ability work automatically he should instead use it by himself for his advatage. This techique can be done with a normal sword as well.