You Call That Service?, Vol. 5 (light novel)

Diplomatic relations between Japan and the Sacred Blood Empire are stabilizing, and
the news has taken the vampire community by storm. Meanwhile, something strange is
happening to Ryouta—he’s transforming into a minion! It turns out that Archbishop
Alfoncina’s prayer for his safety had some serious side effects, and they can only be
cured with an herbal remedy sold exclusively in Japan. As luck would have it, the
archbishop was already planning on traveling there for business, so she invites Ryouta
to tag along. Needless to say, certain people are none too pleased with the
arrangement...