I've some runs and i noticed that runners use japanese instead of english, and i dont understand why, so if possible can someone explain to me why that happens? Is it a method for saving timer or something? Thanks a lot

Japanese is faster in Chapter 1 by about 13 seconds due to a large amount of unskippable text that you have to wait to scroll (Entering the Castle before the Lancer Fight, Prison Lancer Fight, etc.)

Japanese is only just faster in some Chapter 2 categories (e.g. about 1.5s in Main Route Glitched, 0.267s in Main Route NMG/Glitchless) as there's less unstoppable text, and there's a couple spots that lose time. In fact, it loses time in Chapter 2 in Snowgrave categories (2 frames, 0.067s). This is usually only used in Chapter 2 by the highest level runners, or if it's the runner's preference.

It's worth noting in Chapter 2 however that one of the words that Berdly can randomly spell changes from Prodigy to Wise, saving close to 2s, basically making that section faster on average in Japanese.

It's also worth noting that All Chapters categories somewhat recently changed the timing rules to allow the Chapter transition time to not be included. So in the past, some runners would opt to not change language as it loses time too. With the rule changed, now runners can switch from Japanese to English after completing Chapter 1 with no consequence in their final time due to switching it.

ok thanks a lot