Naoki Ishida began as a disinterested Miyaji Academy student, lacking passion until following classmate Aichi Sendou to Card Capital. Receiving a Narukami trial deck and experiencing his first cardfight sparked his interest, leading him to purchase the deck and seriously explore Vanguard. This reflected on how the game transformed Aichi, contrasting their earlier elementary school days where Naoki had been distant.

His aggressive early style featured minimal guarding, favoring offense and leaving him vulnerable late-game. He specialized in Eradicator-type units, building strategies around Vowing Sword Dragon and later Gauntlet Buster Dragon for field control. His deck evolved through iterations focusing on rear-guard elimination and powerful limit breaks. A significant rivalry ignited with Shingo Komoi after Naoki lost a match attempting to "teach him a lesson." This defeat prompted Naoki to request training from Shingo, forging a competitive bond that deepened into friendship.

During Miyaji's match against Hitsue High, Naoki faced Toshiki Kai, pushing Kai to five damage before losing. Kai acknowledged his effort and agreed to future matches. Later vying for Cardfight Club co-captaincy against Kourin Tatsunagi, Naoki lost narrowly but was appointed co-captain by consensus, recognized for his passion and commitment.

Corrupted by Maki Nagashiro when Link Joker reversed Miyaji Academy, Naoki was restored after losing a cardfight to Aichi, recalling Maki's role and joining the liberation. He confronted reversed Shingo, defeating him using a collaboratively built deck and his new ace unit, Eradicator, Tempest Bolt Dragon, restoring Shingo's memories. Naoki then defeated Maki, rejecting her claims about his loner nature and freeing the academy.

Following a universe reset, Naoki temporarily forgot Aichi but regained memories after a cardfight with Kai triggered an emotional response. Encountering Mores, who claimed knowledge of Aichi's whereabouts, Naoki survived Machining Spark Hercules' limit break. Hearing Kai's encouragement, he rode Brawler, Skybeat Dragon and used Legion with Brawler, Skyhowl Dragon to win. He participated in locating the Quatre Knights' hideout and trained at Leon Soryu's residence, persistently improving his deck despite repeated losses. During the final confrontation, he volunteered to fight Raul Cera, believing himself the weakest link, resulting in a planned loss that broke one of Aichi's seals.

In conflicts against Ryuzu Myoujin, Naoki participated in Plan G, overloading the GIRS System using Eradicator, Gauntlet Buster Dragon alongside global fighters. He joined the raid on Ryuzu's base, combating security forces physically, and contributed stride energy during the final battle to support Chrono Shindou's victory. During the Vanguard Koshien tournament's High School Arc continuation, Naoki sought redemption against Kouji Ibuki for past insults toward Aichi. Entrusted by Aichi with the finals' decisive match against Ibuki, his intensely passionate fighting style stirred strong emotions in Kourin Tatsunagi.

Naoki consistently used Narukami decks centered on the Eradicator archetype, featuring key units like Vowing Sword Dragon, Gauntlet Buster Dragon, Tempest Bolt Dragon, and Skybeat Dragon. His playstyle emphasized overwhelming offense and field control, though early-career tactical imprecision sometimes caused overextension. Deck modifications, such as adopting Linchu as his first vanguard for strategic advantage, reflected his growth. His initial reclusive nature and misinterpreted bullying demeanor softened through friendships. He demonstrated fierce loyalty, protecting Aichi from bullies and shielding Kourin from aggressive fans. He respectfully referred to Misaki Tokura as "Boss" and maintained a close, supportive dynamic with Shingo Komoi.