|Engish voice||Barbara Weber-Scaff (2004-2007)|
|French voice||Guylaine Gibert (2003-2007)|
Hiroki Ishiyama is Yumi's nine-year-old younger brother and a fellow student at Kadic Academy. Although Yumi is usually annoyed by Hiroki, she still loves him, as shown on numerous occasions. He is the only son of Mr. and Mrs. Ishiyama.
Hiroki is usually portayed as a typical bratty brother. He is portrayed to be a somewhat mean to Yumi, but in a brotherly kind of way. He will usually help Yumi in exchange for her doing him favors, such as doing his homework for him. He loves to ask Yumi "if she is dating Ulrich?" He is shown to deeply care about Yumi when she is in danger. He is shown to be madly in love with Milly, but does not know how to act on these feelings.
Hiroki frequently tries to get Yumi and Ulrich to go out with each other, and has openly told Johnny that he has no hope with Yumi.
Hiroki first appears in Exploration, in this episode he appears as a bratty little brother. Hiroki is present at the family's game night and is playing a video game on what appears to be a Nintendo DS.
Hiroki's next appearance is in The Chips Are Down where he is at the table when his father says that he was unable to find work at the temp agency. He is later shown to be present when the Ishiyamas's win the lottery, through Ulrich's cheating.
In A Bad Turn, Hiroki call's Yumi to ask her to save him and his family from the big monster. Hiroki watches as his father and later Ulrich defends against the monster's attacks. When Ulrich cut's off one of the monster's legs Hiroki runs towards him and the monster. This causes Ulrich to get knocked unconcious by the monster.
He also appeared in False Lead, letting Odd's Tamaguchi get destroyed.
He appears again in Skidbladnir and does Yumi a favor so they can free Aelita and Jeremie.
He also appears in A Space Oddity and he takes care of Kiwi.
- Exploration (debut)
- The Chips Are Down
- A Bad Turn
- Attack of the Zombies
- A Fine Mess
- Franz Hopper (episode)
- The Key
- Skidbladnir (episode)
- Hot Shower
- Lost at Sea
- Distant Memory
- Canine Conundrum
- A Space Oddity
- Music to Soothe the Savage Beast
- Cold Sweat
Appearances in other Media
- Hiroki is an excellent lock picker.
- Judging by how much he plays video games, he seems to be a decent gamer. He owns a Gameboy Advance SP.
- Hiroki is a terrible listener.
- Hiroki is great with dogs.
- He knows Morse code, as does Yumi.
Hiroki is a romanized Japanese given name with several possible meanings depending on how it is written. Ishiyama is the romanization of the Japanese family name 石山, which means "stone mountain".
- He is a minor recurring character.
- Despite his relation to Yumi, Hiroki is neither seen nor mentioned for the entire first season.
- In A Space Oddity, Hiroki called Kiwi "Leechie".
- 'Hiroki' is a Japanese word for "Abundant joy/strength".
- He does not make any appearances in Code Lyoko: Evolution, but is mentioned by Yumi in False Pretenses.
- In the Finnish dub, he was voiced by Hanna-Maija Nikander.
|Jeremie Belpois | Aelita Schaeffer | Odd Della Robbia | Yumi Ishiyama | Ulrich Stern | William Dunbar|
|Sissi | Jim Morales | Suzanne Hertz | Anthea Schaeffer | Mr. Delmas | Laura Gauthier | Franz Hopper|
|Kiwi | Herb Pichon | Nicholas Poliakoff | Amelia "Milly" Solovieff | Tamiya Diop | Hiroki Ishiyama | Johnny | Takeo and Akiko Ishiyama|
|X.A.N.A. | Monsters|
|Professor Tyron | Ninjas | X.A.N.A. William|
|Jean-Baptiste Pujol | Theo Gauthier | Emily LeDuc | Taelia | Samantha Knight | Samantha Suarez | Heidi Klinger | Mathias Burrel | Magali de Vasseur | Claire Girard | Brynja Heringsdötir | Patrick Belpois|
|X.A.N.A. Aelita | X.A.N.A. Odd | X.A.N.A. Yumi | X.A.N.A. Ulrich | X.A.N.A. Franz Hopper | X.A.N.A. Anthea Schaeffer | Jeremie Clone | Aelita Clone | William Clone | Subdigitals|