(Jikkyou Powerful Pro Yakyuu Heroes) Question about .RDB/.RDI file formats

[nowthatweareseparated]

Hi, I'm new here so apologies if this is the wrong place to ask a question like this or if my question is worded weirdly. I've been trying to rip the sprites of every character in the game. Citra has a texture dumping feature I can use but I'd prefer getting the sprites I want all at once. In the RomsFS folder, there are two files I have a question about, RES00.RDB (145,172 KB) and RES00.RDI (51 KB).
I can't find anything about the .RDB/.RDI file formats online, and I can't open them with EveryFileExplorer. I checked this site and somebody else was also trying to rip from PawaPuro Heroes, but couldn't figure out how to extract from/open RES00.RDB and RES00.RDI, and somebody else commented that there were no programs that could extract from/open these files (That was from 2017). I'm just wondering if anybody can give me any insight about these files, I really appreciate it.

Edit: Just woke up and realized my original post is really vague so I'm going to reiterate, Does anyone know if there is a way to open or extract from the .RDB/.RDI files inside PawaPuro Heroes? Is it similar to another file format that can be opened/extracted? Or has nobody been able to figure out how to do anything with them?