Prepared or not, Batman still stands on a far higher ground than the Kisaragi gang, due to more than a decade's worth of training and a highly advanced education. Batman may actually still win even if caught unawares, since Sachiko mostly still has the mentality of a little girl, and Batman is very good at formulating plans and strategies within seconds. Batman deals with supernatural forces on a daily basis as a side effect of being in the Justice League, so Heavenly Host wouldn't be any weirder than Valhalla, for instance.
That being said, Batman is still human like any other, so Sachiko and her ghastly consorts have a homefield advantage in that their capabilities are unhindered and unbound by logic.
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Official Take-Mikazuchi of the Shin Megami Tensei IV board.