Great. Here comes the usual katana worship in these types of manga. Wasn't it explained previously that changing form used huge amounts of mana both during the transformation and after? Why would he stay in that form in the world of this story?
@MushyMushy The starting version of Form Change, Shapeshift, used a lot of mana. It's insinuated that Form Change is far more efficient. My personal assumption, though, is that Form Change is essentially a semi-permanent skill that doesn't use mana once the form has been solidified. It's only when the form of the sword is being changed that it uses mana. Hard to know for certain since it wasn't directly explained, though, so I could be wrong.