The heir of a dojo hires the protagonist as her bodyguard. In the past her brother tried to burn down the dojo and so he was kicked out. After many years he comes back, beats the protagonist and kidnaps his sister and takes her to an island. The protagonist goes to rescue her and fights the bad guy. Both of them can bring out this long nail/claw thing from their arm. It's not Kure-nai.

Thanks in advance ^.^

are you sure its not Kure-nai because that sounds very similar

To be honest I'm searching it for another person and he said that he is pretty sure that it's not Kure- nai, that's why I posted it here. Thanks for your time ^.^