Haru is a teenage boy with fair skin, green hair that sticks up at the top, and blue eyes. He wears yellow goggles on his forehead. He wears a red track jacket with yellow hemlines and a yellow horizontal on each sleeve and a white "X"-like symbol on the left side of the chest. Underneath, he wears a white shirt. He also wears blue capri jeans with rolled up cuffs, yellow socks, and white and red sneakers.
Haru is a kind and gentle person. Though a bit meek and emotional, he has a strong will and makes decisions based on his own opinions. He loves to read, and longs to be the hero of his own story. He is curious and possesses good deductive skills.
Leviathan's profile on him states that his birthday is July 1, his age is thirteen-years-old, his height is 158 cm, his blood type is O, and that he is right-handed. He is in class 1-C at Fujimizaka Middle School.
- Haru Shinkai (新海 ハル)
Name used in and official romanization given by Digimon Universe: Appli Monsters.
- Ja: Shinkai (新海?). Japanese surname that means "new ocean". Possibly a reference to the Net Ocean.
- Ja: Haru (ハル?). A Japanese gender-neutral name. Possibly from HAL 9000 (ハル きゅうせん HARU Kyūsen?), a fictional computer from 2001: A Space Odyssey.
On October 1, 2016, Haru is checking out books at Fujimizaka Middle School's library, unaware that he is under observation. He heads out and sees his friend, Yuujin Oozora, playing soccer while his crush, Ai Kashiki, watches. Distracted by Ai, Haru takes a soccer ball to the face. Yuujin then sees him, deciding to head home as well. The two of them discuss each other's main character qualities before parting ways. Haru is then notices that a vending machine is displaying his name, which then asks if he is a main character. As he wavers over his choice, the vending machine suddenly entrusts him with an Appli Drive. Haru takes the device home and plays with it, while Cameramon reports his actions to Leviathan.
Deciding to search for more information, Haru attempts to use his smartphone only for Gatchmon to emerge from it. After Gatchmon explains the concept of Appmon, he declares Haru to be his Buddy, though Haru refuses. Gatchmon begins to fade, however, having exhausted his personal power in the Real World. Haru's attention is then drawn by his mother, whose messaging app is on the fritz. Gatchmon reveals that an virus-infected Messemon is the cause. Messemon proceeds to reveal embarrassing images to world, including Haru's bed-wetting photos. After Ai and her own embarrassment over a bad haircut photo and then Yuujin stepping up to the plate to comfort her, Haru flees in shame. They discover Messemon fleeing into an AR-Field, and Haru and Gatchmon give chase. Messemon attacks the pair in there. Gatchmon calls on Haru to appliarise him, but Haru is too scared. Despite being in his weak chip form, Gatchmon defends Haru, telling him that he has confidence in him. Seeing Gatchmon's stubborn drive and pain, Haru eventually decides that he does want to be a main character, unlocks his Appli Driver, and appliarises him.
Now at full strength, Gatchmon attempts to scan Messemon for a weakness, but the relentless attacks prevent him. Haru aids him with a keyword, allowing Gatchmon to perform a search and realize Messemon's weakness: that words can only do damage if you let them. Gatchmon uses this idea to simply ignore Messemon's attacks, allowing him to get close enough to attack and purge Messemon of the virus, obtaining Messemon's Appmon Chip in the process. The partnership cemented, the pair exit the AR-Field. Haru has another conversation with Yuujin, who notes Haru's changed outlook, while Haru's mysterious watcher upgrades him from a main character candidate to main character status.
On October 8, Haru heads to Kashinoki Books, meeting Yuujin on the way. There, they listen to Takeru "Watson" Wato's woes due to his navigation app going on the fritz, which prompts Ai's father to realize that Ai has not returned from her errand. Haru immediately proposes a search for her, which causes Yuujin to comment on his proactiveness. While searching, Gatchmon reveals to Haru his investigation into Leviathan and the L-Virus that has been infecting Appmon. They then come across the virus-infected Navimon, who has been the problems with the navigation apps. While they give chase, Yuujin calls Haru to tell him that he found Ai and escorted her home; this frees Haru to enter an AR-Field against Navimon. Navimon proves a difficult foe, but after searching for a way to confound Navimon's homing powers, Haru applink Gatchmon with Messemon. Gatchmon then manages to defeat and purify Navimon, leading Haru to obtain his Appmon Chip. Immediately afterward, they are attacked by Cameramon, who blinds Gatchmon. Haru desperately thinks of a way out and then attempts to applink Gatchmon with Navimon. He accidentally performs an App Fusion instead, calling DoGatchmon. DoGatchmon forces Cameramon to flee with one attack.
On October 15, Haru discusses DoGatchmon with Gatchmon and Navimon, learning that, while most Appmon can Applink with each other, certain pairs of Appmon instead perform a fusion, combining and increasing in grade. Gatchmon mentions that it will take a while for DoGatchmon to be able to be appliarised. Yuujin calls for him afterward, and the two head to Kashinoki Books to hang out, where they find Watson and his friends discussing Fantasy Saga. Watson, however, discovers that his high level character has been reverted to base while missing his legendary equipment, a phenomenon which soon spreads to the others. Haru observes Ropuremon exiting from his smartphone, so he and Gatchmon give chase, ending up back at school. An AR-Field exists, which has turned the school into a recreation of the Amusing! Exciting Dungeon video game. Haru finds great excitement in the subsequent dungeon crawl, though Gatchmon is annoyed.
At the end, they find a despondent Ropuremon who is angry that they used a walkthrough to make it to the end. After Gatchmon accidentally pushes Ropuremon's berserk button, he grows into a huge size befitting a final boss. Haru attempts to appfuse DoGatchmon once more, but the fusion fails, forming the ineffectual Sukasimon instead; Haru attributes this to Gatchmon's and Navimon's discord. Right before Ropuremon can strike down Gatchmon, Haru tells Ropuremon that he honestly enjoyed his adventure. Seeing Haru's sincerity allows Ropuremon to purify himself of the L-Virus, and he surrenders his Appmon Chip while revealing himself to be a 7code Appmon. Haru obtains the Appmon 7code PAD in the process. Gatchmon believes that gathering all the 7code Appmon will unlock a power that will allow them to face Leviathan, so they make it their goal to obtain all seven.
On October 31, Haru is reading up on artificial intelligence while Gatchmon chomps at experiencing Halloween. Eventually, Haru tires of Gatchmon annoying him and tells him to head out on his own, which Gatchmon proceeds to do. Later, Haru is remorseful, and even more so when Cameramon hijacks his friends' photos to send him a message that he has captured Gatchmon. Haru immediately heads to the appointed place, where Cameramon's henchmen Men in Black display a tablet in which Gatchmon is held captive. Cameramon demands Haru's Appli Drive in exchange. After asking Gatchmon questions and hearing his pleas to be saved, Haru realizes that this Gatchmon is fake, as the real Gatchmon would never give up so easily. He tries to flee, but Cameramon orchestrates a city-wide manhunt for him by painting Haru as the objective of a Halloween event, with a prize to the one who traps him. Despite Haru's best efforts, he is unable to dodge a literal city full of cameras keeping watch for him, and the Men in Black catch up. Gatchmon saves him right before his Appli Drive can be taken away, and the two flee. Haru apologizes on the way and explains the situation, but Gatchmon waves it off as they are Buddies.
Haru and Gatchmon then enter an AR-Field to both escape their pursuers and confront Cameramon. Cameramon reveals that the power of App Fusion is not theirs alone, as his Buddy appfuses him with Shotmon to form Scorpmon. Scorpmon's unerring shots due to his mastery of surveillance prove even a match for DoGatchmon once Haru appfuses him. Haru remembering during his earlier ordeal about blindspots and uses that knowledge to plot a route that allows DoGatchmon to sneak up on Scorpmon. In melee range, DoGatchmon easily defeats Scorpmon. Haru obtains Scorpmon's Appmon Chip but Mienumon rescues him. Haru and Gatchmon then exit the AR-Field and fully reconcile over sweets.
On November 3, Haru is talking to Gatchmon when his television catches his attention. On it, he sees a blue Appli Drive in the possession of an Appliyama 470 idol named Eri Karan. Deciding to follow up on the existence of more Appli Drives, he and Gatchmon sneak into the television station where Eri is being interviewed alongside other members of the idol group. They end up in her dressing room and introduce themselves, with Eri being excited to meet someone else with an Appli Drive. Eri reveals her own Buddy Appmon, Dokamon, who remains as an Appmon Chip in contrast to the appliarised Gatchmon. Before their discussion can continue, fashion apps go on the fritz, with a viral Dressmon as the culprit. Haru and Gatchmon chase Dressmon into an AR-Field, dragging Eri and Dokamon along despite the former's reluctance. Within the AR-Field, Dressmon's attacks prove strong enough to stall Gatchmon, and they are forced to retreat. As Haru and Gatchmon try to plan an attack, Dressmon shreds their cover and traps Gatchmon. Dokamon pleads with Eri to appliarise him to fight, and Haru charges her with the same. Eri decides to step up to the plate and appliarises Dokamon, driving off Dressmon long enough for Haru to free Gatchmon. Eri then lends Haru Dokamon's chip to allow him to applink Gatchmon with Dokamon. The pair are able to defeat and purify Dressmon, returning the fashion apps to normal. That evening, Eri recounts the events that led to her obtaining an Appli Drive, and they part ways after exchanging contact information.