Takashi Yamazaki is a student in Sakura's class and one of the first named male classmates we meet—before Syaoran even shows up. His character is named after real film director Takashi Yamazaki, who's friends with CLAMP, the series creators.
Yamazaki's whole thing is making up elaborate, convincing stories about basically anything. He's good at it too—like, surprisingly detailed. Most classmates catch on, but Sakura and Syaoran tend to fall for it. Later in the series, when Eriol joins the cast, the two of them become storytelling partners and can riff off each other's lies perfectly, no hesitation.
Chiharu Mihara, another classmate, basically exists to call him out. She'll interrupt mid-story to expose him, then "punish" him by fake-strangling him or dragging him away by his collar—which sounds harsh, but they're actually a couple who've known each other since kindergarten. She's the only girl he calls by her first name. And despite all his joking around, he does have a genuine side: he'll rush into dangerous waves to try saving a drowning classmate, and he knows when to step back and give Sakura space when she's dealing with her feelings for Syaoran.
The anime plays up his character design quirk—his eyes are almost always closed. His relationship with Chiharu stays vague in the adaptation too, though a vision on the Day of Judgment shows them as complete strangers if they'd lost their feelings for each other.
The English dub (Cardcaptors) changes everything: he's renamed Zachary Marker, made Chiharu's cousin, and all romantic subtext disappears into just sibling bickering.
Voiced by Issei Miyazaki in the anime, Philip Pacaud in Cardcaptors, and Joshua Seth in the second film's English dub.
Content compiled by AnimeList.moe from publicly available sources.