No, I don't know japanese, but it's something I found out while browsing: Some glyphs at some font sizes are broken. Glyphs that are broken: Sazanami Mincho U+8449 U+8870 Sazanami Gothic U+9090 U+9115 (source http://wiki.fdiary.net/font/?sazanami ) That would mean it's an upstream bug, but does that count for fonts ?
Sorry for the delay. Right, this is a bug in upstream, and they already know it. They planned to release new version this summer, but they didn't. Hope they get some time to fix and release new version.