There is a nasty bug in Unity which enforces some dirty hacks in Naninovel codebase. It’s been reported half a year ago, but doesn't have a lot of votes, so Unity is not bothering to fix it.
I’d really appreciate the votes for it on the tracker: https://issuetracker.unity3d.com/issues ... -play-mode.
Hopefully it will be handled before 2019.4 LTS release, otherwise we’ll probably have another bump in minimum supported version. :?