There is no proof of any of this. One fuzzy photo from behind of Mona with a guy to the right of her and a girl to the left. This is supposedly when they were out at a big park in Niigata looking at cherry-blossoms in the evening, and the girl with them is supposedly Neru (and could be). Let's see: bringing in a third wheel is not exactly what you do when you want to be with a boyfriend.
The guy was asked, according to Bunshun, and said he and Mona were friends from middle school, not romantically involved then or now, and that he had been worried about her ever since she entered Keyakizaka, that her health seemed to suffer. The pic of the three of them was supposedly taken when they were out looking at cherry-blossoms in a well-known park in the evening. On the day after the last of the three anniversary concerts.
In other words, concocting a story from almost nothing. 2channel antis have gone nuts, especially since Neru is involved. The word "tanuki" appears frequently, lol. Over 7000 posts in less than twelve hours. I haven't read much of it, but it just seems like an anti- festival, without real content. Neru continues to have many low detractors.
This also has no proof, but just to add to the confusion I'll repeat a rumour that Mona's problem is that she had a stalker and he ended up being harmed (killed?) in front of her (not by her bodyguard). This naturally had serious emotional effects on her, according to the rumour.
The main thing I get from this is that Neru is a good person, having gone off to Niigata to cheer up Mona. But the piece could still have harmful effects. Some wota are completely irrational about any actual guy being anywhere near their idols. We'll just have to wait and see.
source1 source2 source3(partial story on Bunshun's website) source4
Support page with many good photos of Mona.
via Anakamirikarutenani