Yes, Han-Latin
means pinyin. ICU transliterators come from CLDR (I'll update the userguide to make this clear). ICU already can convert kana (hira/kata) to latin, but Kanji has more than one reading, so you won't find what you are looking for with a simple table-based conversion.
edit: so to summarize, ICU will not do what you want without writing rules, nor does it seem to me likely to be simple to do with your own rules due to how the Japanese language works.