[Joseph Jostar]

Despite only being available in the 'Coral' material, Sea Hunter Tome's material type is still treated as 'Chapter' instead of 'Metal'. This was tested with material change kits, Chapter kits being applicable to the item and Metal kits being unapplicable. Additionally, if changed to a Chapter material the tome is not able to be returned to 'Coral'.

This presumably holds true for the Sea Hunter Bow, which is also made out of an unorthodox material for its weapon type (metal bow instead of wooden).

[Neus]

Not really a bug, just how it is.