Hit F2 - it's the service mode.
In fact - everyone hit F2 to get into service mode on games that have a service mode.
With some searching I figured it out. Although getting to service mode just introduced a new problem: everything is in Japanese! But I found this elsewhere.
- select 7th line (labelled 7) with button 1 (well it's simple, the game only allow 1 button)
- select first line (labelled 1) press button,
- select the 7th line and toggle through the 3 options. 1 has an 8 in it, one has a 2, and one has just the glyphs. Choose the glyphs.
- select the last line, press button
- select last line (labelled 4) press button
- select last line (labelled 9) press button
Worked like a charm.