An unknown individual is out to target the Protagonist, by targeting him/her with Ink Bombs.
Why? Let's find out!
Mysterious Pranks
As the Protagonist leaves his/her house, a bucket drops down next to him/her out of the blue. The Protagonist is surprised at it and finds a note, saying that it's only the start of that persons revenge.
The Protagonist decides to keep an eye out for more pranks.
Shortly after, the Protagonist's mail box is filled with mails. Each of them seems to have a small lump inside of them. If the Protagonist decides to open them, the letter will get stained with some blue ink, implying that the Ink Bomb was turned the wrong way.
Otherwise, if the Protagonist decides to dispose of them in order not to take any risks, the Protagonist remarks that it was weird.
The next prank happens at the Lake. The Protagonist finds a sign with a rope next to it - the sign tells the Protagonist to pull the rope. If done, a bucket falls down on a person who is implied to be the one who set it up, who then hurries off.
Otherwise, the Protagonist hears "what sounds like a female voice cursing [the Protagonist]".
The Shop
In the Item Shop, the Protagonist runs into a mysterious person who is supposedly purchasing a large amount of Ink Bombs - and has been purchasing quite a lot of them lately.
The person instantly tells the shop keeper off, saying that she's paying for them, isn't [she]?
The shop keeper explains that they're not exactly hurting for her business, causing the person to say that she's only after one item, but they apparently can't sell her that.
When trying to explain that it doesn't quite work like that - they have to make a whole new potion and such, the person remarks "Wait until [she] gets [her] bo-" but is cut off at the Protagonist entering the store and instead hurries off without saying anything further.
Target for Revenge: Cassandra
At the School, Cassandra is visibly irritated at someone targeting her with weird pranks.
The Protagonist can either admit to it happening to him/her, too, causing Cassandra to say that they need to put a stop to it. The Protagonist asks if she has an idea, to which she says she does, but then hurries off in order not to rouse suspicion.
Otherwise, the Protagonist can remark that it sucks for her, causing her to bluntly say she's aware of this fact and leaves in order to find out who's behind it all.
This is as far as the route goes as of version 0.39.