unless you live in a tropical place then you are exempt from the staying warm rule like Sein here.

Synxirazu-niam drew the lines and coloured the jacket, while I finished it off by colouring in the character which is why you may notice it seems like two different colouring styles are present.

Sein the mako shark belongs to deskai of Fousen Works
lines and jacket colouring to Synxirazu-niam of Fousen Works
Colouring of Sein to Deskai of Fousen Works