The pacific campaign introduced the new bayonet charge mechanic into the game. Though it is not unique to the pacific, this was one of the main features the pacific launched with. With this feature in the game, melee is more viable as you can charge into the enemy faster. I propose making a truly unique squad for Japan focused on melee. Would a squad like this be any good, or at all viable compared to other squads? No.
The Stalingrad update added the night witch premium squad to the game. It is a “collector squad”, which means its really bad. This sets a precedent that other really bad but fun squads can be added.
The pacific campaign is both early and late war. Near the end of the war, Japan feared a land invasion, with limited guns and resources they prepared to fight with whatever they had. This means a spear squad of Japanese soldiers could make historical sense.
This set of miniatures is a bit extreme, I am not saying they should be famished.
TLDR: A melee-focused squad with spears for Japan could be really unique and fun. It would be a bad squad, but the developers have added purposefully bad squads before.