Leonardo

Leonardo is a Human Assassin-Delivery Man from the North American server. A month after the Catastrophe, he fled from the Big Apple due to the riots and lynching after the discovery of Real Food Preparation and a subsequent attempt to monopolize the secret. After hopping into a Fairy Ring, he found himself in China, where he was eventually found and rescued by Kanami's Party, which he joins.

His Overskill is Parallel Plot.

Appearance
Leonardo's overall appearance was intended to resemble an anthropomorphic ninja turtle that wears a green mask, only covers his eyes, and has two katanas; though Kanami remarked that Leonardo's headgear had made him look more like a green Umibouzu, and then later a frog as Kanami had one time called him "Kero-nardo." Kanami was able to easily recognize what comic character Leonardo was trying to imitate and found it humorous.

Due to copyright laws, Leonardo's appearance was changed to look more like a frog's for Kanami, Go! East!.

Personality
Leonardo is apparently a huge fan of Teenage Mutant Ninja Turtles, and coincidentally was born in the same country and state of his favorite characters. He chose a certain sword wielding turtle because he thinks it looks cool. Born as a New Yorker, Leonardo has his sense of pride and believes that being a turtle ninja was to be an ally of justice. Like Akatsuki, Leonardo is apparently devoted to role-playing.

Leonardo appears to be well-versed in the lore of Elder Tale, even being able to recite Elias Hackblade's backstory to him.

Before the Catastrophe
Leonardo has been playing Elder Tale for five years, with his usual home city as Big Apple. He was well known, although more because of his bizarre appearance than his actual skills.

He was a computer engineer in real life, and had worked on projects with people from various countries.

The Catastrophe
After the Catastrophe, Leonardo stays in the Big Apple until the June Riots break out, causing him to first take refuge in the sewers before jumping through a Fairy Ring. He is subsequently stuck in Tekeli, a remote town on the Chinese server area, after accidentally triggering an event that summons hundreds of enemies. There he stayed, dying over and over again before Kanami, Elias Hackblade, and Coppelia arrive, en route to the Yamato server.

Go East! arc
Leonardo masters his overskill by chaining skills before their animations are finished. This proves handy in the confrontation with the Genius monsters Rasphuia and Papus, when he single-handedly kills Rasphuia by cutting through her ability.

Krusty, Tycoon Lord arc
During the exploration of Sirius Grotto with Kanami, Coppelia and Chun Lu, the cave collapses due to the duel between Krusty and Elias above ground. Eventually, he and Coppelia come across Kanami kiting an insane Elias; he separates Elias from the rest of the combatants to have a duel with him. The conclusion of their duel comes when Krusty kills Papus for good, thus freeing Elias from the monster's grasp; Leonardo has been reduced to well below 25 percent of his HP, illustrating how Elias has broken past his in-game constraint. Leonardo then recites the origin of this mechanic: that Elias doesn't want to kill, and that this mechanic was meant to be a crystallization of said pledge.

In the anime, Leonardo is seen with the rest of Kanami's party at the communications equipment at the bottom of Sirius Grotto.

Drama CD: Kanami, Go! East!
Taking place after the events of the Go East arc, Kanami's party continues on their journey towards Akiba. Kanami stops the group to look at a sunset, much to Leonardo's annoyance. After some banter between himself, Elias, and Kanami, the party leader asks Coppelia where Japan was. Knowing that Kanami didn't actually understand Coppelia's sentence, Leonardo interjects that they were walking in the complete opposite direction of Akiba.

Kanami, realizing this, bemoans that such "trivial things" were always left to "Shiro-kun", much to Elias' and Leonardo's confusion. After describing who "Shiro-kun" was, Kanami wonders aloud how he and the other Debauchery Tea Party members were, and affirms to Elias that seeing them was one of the reasons why she was heading to Yamato. Annoyed, Leonardo comments that she had stated that her purpose of visiting Yamato was to find out the reason behind the Catastrophe, only to be told that visiting "Shiro-kun" and finding out the answer was one and the same.

Whenever Leonardo heaves a sigh of annoyance, Coppelia asks him if he needed healing. Eventually, Kanami gets bored of watching the sunset and tells her party to head east.

Trivia

 * Leonardo's "COWABUNGA" leap was, in-story, inspired by the 104th episode, "Jump, Froggers!", of his favorite show (which is a parallel-universe frog version of the Teenage Mutant Ninja Turtles). The 104th episode of the original TMNT 1987 cartoon series was titled "Unidentified Flying Leonardo."