Ohhhhhhh... That's why Raiza is being a bit awkward to Saito and being blushy in the first batches of chapters.
Now we already know the answer.
Next would be a little push for Saito for them to officially couple which I ship them and supported it truly
when everyone were talking about mushroom, i took a long of time for searching the archive in my brain for what it was and then knowing the horror that have been sealed.