User can turn into a katana

Pros:
-user has a cover
-user is always sharpened
-user can make hair into blades in human form
-user can use blades as claws
-user can change size of blade they become

Cons:
-user will still harm others with blade
-user is very weak in human form
-user will rely on quirk quickly

Weakness: training
User will be careless when not trained and will harm others