It seems that there are already some duplicate tags, such as ruroni-kenshin and rurouni-kenshin (and another one just by the name of kenshin). How should we act regarding different romanizations of the Japanese titles? I'm thinking that the first one should be suppressed, and everything tagged with it retagged with the second tag. Or maybe different spellings are allowed and synonyms created?
Considering that accents are not allowed in tags, I would say that we should use the non-accented romanized spelling for titles. Rurōni Kenshin with one "o" is only appropriate because of the use of Hepburn-style romanization using the macron for the long vowel. Rurouni Kenshin is the most correct form that we can use in the tagging system, so I think we should default to that.