Board Thread:General Discussion/@comment-28224025-20180803155658/@comment-4436931-20180813000656

Kisugi Teppei wrote: Mitsuko has her name in english but in japanese it's "Haizaki's Mother"

I believe it's mentioned in the episode

In Aki's page Tenma is her nephew, although in Tenma's page Aki isn't his aunt... then again, pretty sure the whole thing is wrong

This was confirmed in a magazine interview. You can find it a couple threads back