Most handheld and console games until things started being basically PCs will use bitmap fonts, vector stuff has common on PC for a while and creeps in on said might as well be a PC consoles. You tend not to have hardware guided formats like you might have for some other things either, and when you do it is more the really old "home computers" that have such things baked in somewhere (though the PSP can have an element of this at times).
Some will be nice regular images (textures implies 3d aspects and all that follows, 2d stuff being more than adequate for most font needs, and while some consoles have 2d as a consequence of projecting a texture onto a flat surface... eh). Some will be per character/glyph/rune/... sizes at graphics level, possibly with character data inserted between the tiles to make your life with a tile editor that much more annoying. The PSP being a relatively modern device also means no real restrictions on some of the more exotic aspects of font design (variable width is as nothing, can also do vertical placement for ascenders and descenders). If Sony provided a font format it is not as commonly used by devs as something like ntfr on the DS was (which itself is not that commonly used compared to say the sound and other graphics formats).
If extracting is the goal (as in nice bmp on your computer to maybe use in something else, as opposed to needing it for a RO hack) then the for non Japanese games the entire font might be shoved into memory such that a graphics viewer in an emulator can grab things, for Japanese games with the many kanji likely available then less so. You can possibly still get it done -- if you can find the text (usually a far easier hack) you can do the Japanese equivalent of The quick brown fox jumps over the lazy dog while hammering the print screen button.
