I feel like I missed some character development taking place between TSR and Invisible Victory

NewestPersonHere said:
Most of this information are explained later in the LN, including the history of the 2 organisations~

ShunkaWitko said:
Yes, it's from Fumoffu.

Infamous_Empire said:
The adaptation skipped over one novel between TSR and IV, but its contents aren’t actually super relevant to either of your main questions. With regards to Leonard, he was only briefly in TSR, but it’s made clear in the screen time he has that he’ll be a big deal going forward. The white-haired guy’s introduction was just as sudden in the main novels as it was in the anime, and this is one of those areas where I think Fumoffu really improves the experience, since that’s where he first appeared.

In fact, I feel like watching Fumoffu before IV majorly improves the experience of the latter in general, even beyond the above-mentioned context.