Hart Tenjo

Haruto Tenjo is Kaito Tenjo's younger brother. He possesses a mysterious and strange power that can create paths to alternate realities to which Dr. Faker abuses in order to accomplish his plan of conquering the Astral World and collecting the "Number" cards.

Personality
Haruto appears to have a split personality. When not using his powers, he tends to act quite vulnerable, usually staying in bed, or looking down at Heartland from the Heartland Tower, wondering why he can't enjoy laughter like the people who attend the Heartland Fairground. When using his powers, Haruto sadistically laughs at the Astral World's inhabitants' screams, saying that he "needs more screams" as that is what comforts him. Kaito has also stated that Haruto hasn't been his usual self as in the past he used to enjoy laughter and was playful and talkative.

History
In the past, Haruto lived with his brother in a small, wooden villa where they would play all day whilst Haruto drank his favourite drink, hot chocolate. This happy life was however, disrupted due to the presense of Haruto's powers. Mr. Heartland appeared before Haruto and his brother and told them that his powers are a curse, and that unless Haruto is kept under control, they will get worse thus the brothers had no other choice other than to go with him.

Yu-Gi-Oh! ZEXAL
After hunting the "Number's" of an unlucky duelist and informing Mr. Heartland about his capture, Kaito returns to the Heartland Tower in order to check up on Haruto. He finds Haruto stood at the window of the tower, staring blankly down at the people enjoying the Heartland Fairground and asks Kaito why they are laughing as he doesn't require laughter, only screams to which Kaito shows displeasement. He then asks Kaito if he wierd, to which Kaito says that he is simply in a bad dream and that he will one day wake him up from it.

During Kaito's duel with Yuma Tsukumo, Haruto is ordered to send the trash collected by the Litterbots into the Astral World again. During which he experiences severe pain in his head, causing him to collapse and cry. Orbital 7 monitors Haruto's situation and informs Kaito, causing him to cancel his duel with Yuma in order to run to his brothers aid, saving Yuma and Astral from not only losing their "Number's", but also their lives.

After his trauma, Haruto spends a number of days in bed. To keep Haruto relaxed, Kaito stays at his bedside, making sure that he is comfortable in every aspect, even to the extent that he has a holographic scenery of their old house surround Haruto's room. Despite being ill, Mr. Heartland interrupts and states that Haruto must use his powers. Despite Kaito's protests, Haruto says that he will use his powers as they are causing good for the world, to which surprises Kaito. Haruto then walks with Mr. Heartland who tells Kaito to continue collecting the "Number's" if he wants to save Haruto in time. The two then disappear through a portal.

After Kaito stole Yuma's The Emperor's Key and invaded it. He stumbled upon Astral and asked him about why he is claiming the "Number" series. After Astral answered Kaito, he asked the question back to which Kaito lied and said that he wants to learn the secrets behind the Balian World. After comparing Kaito to Yuma, Kaito snaps at Astral stating that he has no parents and that the only person he has is Haruto, to which Astral ponders but is snapped again at Kaito telling him to cut the conversation and continue dueling.

After managing to get into Kaito Tenjo's Laboratory, Yuma tries to find Astral and The Emperor's Key by pressing random keys on a console, but doing so resulted in making an image of Kaito and Haruto appear to which confused Yuma as Kaito looked happy and to whom the other person is.

Later on Haruto see's Kaito exhausted from collecting the Numbers to heal Haruto. Haruto then sneaks away from Heartland, and by chance meets Yuma Tsukumo and Astral. Amazingly, Haruto can see Astral, who in turn seems to know Haruto's name.