Diciphering a Japanese Teeshirt

Got this email the other day from a guy called Jeremy...

"I stumbed across your website "Visiblemantra.org" on a jaunt through Wikipedia late one afternoon at work, and was wondering if you might be able to help me. I've attached a scanned image of a script on a T-shirt I bought in Japan some 5 or 6 years ago. I've long wondered what it read, but have only managed to figure out that it is written in Siddham Sanscrit - a revelation that took me about 4 years to figure out. Unfortunately, I'm still unable to decipher the entire piece. If it's not too much trouble, could you help me in solving this mystery? Any insight you could offer would be greatly appreciated."

Not trouble at all and I had a great hour or two deciphering it - the results were a bit of a surprise.

First I read the text as the syllables: a i su be ki .te mo (where the .t is a retroflex stop, not the dental t). So far so good, but this seemed a bit odd if it were Sanskrit. Funny to see a and i written separately. I tried a web search and nothing (except the same guy asking the same question on a online forum!) . Tried the Sanskrit dictionary but couldn't find anything that helped. So it wasn't Sanskrit. Had to be Japanese. I started clumping the syllables together and searching Japanese sites. Ai subeki turned up a few references in song lyrics - meaning something like beautiful friend. Then looking at one site I saw the word 'tomo' and I realised that the .te was actually .to - an easy error given the basic .t glyph and the way that the vowel is indicated. So the text turned out to read: aisubeki tomo. It occurs in a song lyric by a Japanese band called Soul'd Out and it means "My beautiful friends". Could be from somewhere else as well of course, but Google doesn't index it.

I emailled Jeremy back with my findings, but as of today haven't heard back.