The Turtle serializer of Virtuoso abbreviates IRIs to prefixed names where possible. So http://example.com/foo becomes ex:foo if an appropriate prefix is declared.
However, only certain characters are allowed in the local part of prefixed names (the foo part). See the Turtle spec:
Virtuoso produces prefixed names when the local part contains certain characters outside of the legal range. Thus, the Turtle output becomes invalid and cannot be read by parsers that follow the spec more closely (like Jena).
The serializer should simply output the full unabbreviated IRI in this case.
A minimal test case is attached. This causes a parse error because of the "star" character used in the triple's subject. If the subject was written as http://ja.dbpedia.org/resource/ダンス☆マン then things would be fine.
The test case is extracted from this live example:
I'm not sure which versions of Virtuoso are affected -- the one used for the site above exhibits the problem.