Jataro has an incredible talent for anything seen as creative, such as drawing, painting and sculpting. He is also shown to be quiet, shy and scatter-brained. The official artbook describes him as "curious, crafty, and fascinated by dark and disturbing things".

Jataro is acknowledged by both himself and those around him for being hated, and he seems content with that fact. He has a tendency to blame himself for things that have nothing to do with him, as well as repeatedly apologizing and putting himself down. He believes that his face is horribly ugly and he panics if anyone wants to see it, claiming that seeing his face would make people's eyeballs explode.

Jataro's thoughts are disorganized and off-topic, some being innocent and some not, and he often has difficulties following conversations. He is shown to have some sort of mental or emotional instability, which becomes evident when he lapses into his episodes of rambling. He describes these ramblings as "yawns", things that come out of his mouth involuntarily and nobody can understand them, not even him. He calls them just "killing of time" and "distraction from the horrors around you".

Jataro's presence is often largely ignored, though he states later to Komaru and Toko that being ignored is something that he doesn't like. After Nagisa Shingetsu becomes impatient during his introduction and interrupts him, Jataro becomes visibly distraught and mumbles how his skin was 'beginning to crawl and itch' and how he wished to 'tear it all off.'

Despite the constant self-deprecation, Jataro is self-described as being a cheerful kid (though he admits that he may not understand what "cheerful" means), helpful to his friends and willing to comply with whatever they ask of him while remaining relatively upbeat.

It's later revealed that Jataro's acceptance of hate is a coping mechanism he developed against the constant abuse in his home life. He also believes that it's easier to be hated, because it leaves him free to do what he wants without worrying about pleasing people.