As a continuation of this problem
https://forums.mirc.com/s...rt=1#Post157425
in the mIRC v6.21, a Japanese channel name in JIS doesn't work properly. Actually this problem has persisted since v6.16. mIRC v6.15 works fine for a Japanese channel name. It seems v6.20 only fixed the SJIS/JIS conversion for channel messages but not a channel name.