|Novel Debut||Volume 9|
No.3 (三番目(達)) is the third and final Heartseed-like being encountered by the Student Cultural Society. No.3 appears in Asu Random I and drags much of Yamaboshi High's student body into an Isolation Dimension. Like No.2, No.3 acts independently from the original Heartseed, who is opposed to No.3.
Like the original Heartseed, No.3 speaks and acts in a slow, lifeless manner, as if bored. Even more so than Heartseed and arguably No.2, No.3 is quite malicious, having no qualms about tormenting the innocent students of Yamaboshi High with phenomenons. Unlike Heartseed, No.3 fully accepts Record Deletion, wishing to impose it on the StuCS and Heartseed.
No.3's reason for sending the first and second year students of Yamaboshi High School to the Isolation Dimension was for experimentation; to see how each group would respond to the phenomenons. Because he didn't want the StuCS to interfere with the Isolation Dimension, No.3 manipulated the other students into believing that the StuCS were the reason for their entrapment. The majority of the student body, scared and confused, quickly became fearful and paranoid of the StuCS.
No.3 does not appear in person, instead choosing to possess a 1st year student to converse with others. While possessing someone, the possessed person adopts a lifeless disposition akin to other possessions.
No.3, like all Heartseeds, is powerful supernatural entity and was able to pull a large number of individuals into an "Isolation Dimension" of No.3's own design where they may be freely toyed with without outside interference. No.3 has displayed the power to invoke numerous phenomenons at once while in the Isolation Dimension, allowing him to affect several groups at the same time, each group suffering a different phenomenon.
Holding an even higher authority than Heartseed himself, it is implied that No.3 may be the leader, or at least an authoritative figure, amongst the Heartseeds. In addition, it is heavily implied that No.3 is not a single being like No.2 or the original Heartseed, but perhaps a group of beings collectively known as No.3. This made the StuCS fear that No.3 could be watching them from anywhere, at any time, which initially made them more cautious of their actions. No.3 did not appear to be aware of the original Heartseed entering the Isolation Dimension, so it would seem he somehow cut his ties and became independent from No.3.