Usually I just leave 'honorifics' as-they-is for Umamusume doujins (Japanese school setting + too many characters to bother to figure out proper unique ways of reflecting them in English, and because there are multiple different translators TL'ing so keeping 'honorifics' helps ensure consistency), but I don't think most people are familiar with -kou (aside from as a respectful title/term of address), so this has to be translated.

NNescio said:

Usually I just leave 'honorifics' as-they-is for Umamusume doujins (Japanese school setting + too many characters to bother to figure out proper unique ways of reflecting them in English, and because there are multiple different translators TL'ing so keeping 'honorifics' helps ensure consistency), but I don't think most people are familiar with -kou (aside from as a respectful title/term of address), so this has to be translated.

-kou 'honorific'

Anyway... Amazon calls the trainer "Tore-kou"/"Tra(iner)-kou". Kou is originally a noble title ("duke"), but can also be used as a respectful honorific for people of high status (or certain real life bigshots).

But when -kou is appended to an abbreviated version of a person's name (like what Amazon does), it acts as a diminutive like -chan, forming a affectionate nickname. This use of "-kou" is sometimes applied to pets, especially dogs. It's kinda like saying snuffykins or snookums.

Using "-kou" this way is rougher than "-chan". It can also be used derogatorily (or both affectionately AND derogatorily), again like adding -kins or -ums or similar to a person's name, e.g. "Jimmikins".

"snookums" haha nice