if i try to log into my machines back in tokyo by IPv6 SSH, it takes very long time. i guess i found the reason - (possible) lame delegation of blah.ip6.int. ip6.arpa. query returns instantly. how could we fix it? By fixing the software as ip6.int was deprecated 2 years+++ ago as you should already know. for backward compatibility reasons many software do query ip6.arpa; if (not found) query ip6.int; i'm not too sure if we can remove the "query ip6.int" part today.
if, as you say, there was instant response to the ip6.arpa query, then jeroen's response that the software was broken seems even more clear. and i don't believe in 'do-gooder' software that tries to make broken things work anyway. if it succeeds, no one notices and says thanks. if it fails, boy does it look bad. randy