Some episodes has subtitles with Korean names like this one.
Daniel Thunberg
2021-10-22 18:49:29 +0000 UTC
Ran-neechan basically meens Sister Ran (neechan - Sister/Older/Big Sister) it's is a common way younger children call girls who is older than them. In the same way Conan calls Heiji-niichan which means Brother Heiji (niichan - Brother/Older/Big Brother)