Prototype Bulin MKII is a special ship that is given out through tasks, sold in the shop, obtained through events or other ways. This ship cannot be built and does not drop from any stage.
She has a special ability, to replace a same-named ship required when performing a Limit Break. She can be used instead of any Super Rare ship making her rather valuable. Like the Universal Bulin, she is however almost completely worthless as a ship to sortie.
She also gives no stats when used in strengthening, so if you end up with too many of her that you don't need it is better to Retire her in the build menu instead.