Problem with textboxes and HUD tiles file

Hello,Im new here so I don't really know that much about anything but let's get to the point!
I'm making an adventure game in japanese but ran into few problems with ingame textbox's.
First of all I located that anything I write in the text section picks up the visuals from correctly placed tiles from the current HUD Tile set (when I type A I get A etc). So I replaced the alphabet tiles with hiragana character tiles so I can somehow type in japanese now. But only somehow. There are 58 characters in hiragana and only 26 in latin alphabet. So is there a way I can use the remaining characters (that didn't have space in my keyboard) in texts?
My next problem is that I run out of HUD Tile sets space with hiragana. The tile set has only 64 "slots" and the needed hiragana would take 58 out of it and I would still need numbers and [!?]. so I wouldn't have any space left for the actual hud graphics ww. So how can I store the text substances I need in some other bank?
I bet there is some kind of FAQ that would answer these question but couldn't find it so I made this thread.
Hope you can understand what I'm uttering because english is not my strong suit.

I'd suggest you to prepare all the texts of your game... on a paper, try to reduce, reuse maximum of the same hiragana you can. To reduce the number as just the ones you need for your game.
Then you can put them on the hud tileset... and replace the ABC tiles... of course you can replace space, "," "." "-", "!" ...etc if you need too
Then (each tiles corresponding to a keyboard character....) recompose your phrases, like pieces of a puzzle.