As tens of thousands gathered at Chiba Marine Stadium to experience Summer Sonic headliner Stevie Wonder, Shunsuke Yano was preparing for his own show on the much smaller River Side Garden stage nearby.

On stage the Japanese rapper joked about the legend next door: “Why the heck did you choose to come here when Stevie’s over there? We have to show our guest some hospitality!”

The crowd laughed; it was one of many laughs Yano, better known as Chinza Dopeness, got that night. At points you might have thought you were watching a comedian instead of a rapper.

In between the laughs, though, 29-year-old Chinza demonstrated a style of rapping that is rare in Japan and his audience quickly got swept up in the vibe.

Chinza’s performances are described by his peers and fans as “alien.” Not alien in a derogatory sense of being foreign, but in an out-of-this-world way. He throws people off with abrupt changes in his speed and flow. Other rappers can’t decide if the approach is genius or not.

However, his “alien” style seems to have the ability to appeal to a crowd beyond the usual hip-hop fan base. He raps, he sings and he tells jokes. One minute he is performing in the grand tradition of New York emcees, and then he’s suddenly on the floor shouting like James Brown. It might be this unpredictability that attracts crowds of all ages.

“I always do what I feel is fun and entertaining,” says Chinza. “I’m lucky that my audience can usually get into what I’m doing. But I’m not trying to do what they want me to do. . . . It’s just like, ‘I’m gonna do this and you should just . . . enjoy it!’ ”

In general, hip-hop fans in Japan can be divided into two scenes. One includes those who are also into J-pop. They listen to artists such as m-flo and Rip Slyme, who usually rap over soft beats on easy-going tracks. These artists’ labels target a wide market, so a clean image is important, as it is throughout most of the J-pop world, in order to achieve “idol” status (whether the artists themselves would like to or not). The other scene consists of fans who are more hardcore, confining themselves to a more closed-off J-rap scene. Image is important here also, but in the opposite sense — these artists must be careful not to look too pop. They include acts such as Tha Blue Herb and Shing02.

Chinza thinks he fits somewhere in the middle of these two groups. He tries to appeal to a wide range of listeners outside the traditional scene, but at the same time he puts a real effort into making sure the focus remains on the art of hip-hop. In short, he doesn’t try too hard to maintain an image — either way.

Last year, Chinza signed with EMI and released his debut album “100% rap.” He admits he doesn’t act like a typical major-label artist (sure enough, we end up riding the same train together after the interview) and says he signed with EMI mainly to get help with touring other parts of Japan. In fact, EMI helped him get the Summer Sonic slot.

“When I do a street gig on some random corner, children and older people, not just hip-hop heads, will stop and listen carefully to my songs,” says Chinza intently. “I really believe these people just get a feeling, maybe some kind of sixth sense, that piques their curiosity. Even if they don’t have an image of what hip-hop is.” He takes a pause, then laughs, “I’m trying to reach out to those who are into hip-hop . . . but not really into it.”

By reaching out to those kinds of fans, Chinza might be reaching out to people in whom he sees a bit of himself. Born in Kunitachi, western Tokyo, Chinza says he first “met” hip-hop when he was a 12-year-old in junior high school.

“There was no one around me listening to hip-hop at the time,” he says, adding that rap in those days was seen as “funny” music. One day he wandered into a local record shop and bought albums by several U.S. hip-hop artists from the 1990s, including his favorite, The Notorious B.I.G.

“Back then, I liked Method Man (from Wu-Tang Clan), Snoop Doggy Dogg, Warren G and Jay-Z. At that time, Smif-n-Wessun and Black Sheep were popular among Japanese hip-hop heads, but I preferred (The Notorious B.I.G.’s) flow.”

Eventually, he tried rapping over some of the albums he’d bought. He recalls one time when he grabbed a microphone in his school’s gymnasium and began freestyling in front of the other kids.

“I remember everyone looked at me oddly,” he says. “In those days, I rapped about things like the environment, shouting, ‘The Earth is in danger, yo!’ “

In high school, Chinza found a partner, Sabo. They still perform together in a group called Kochitola Haguretic Emcee’s on an independent label. Back then, they performed at school festivals and some clubs in Fussa, Tokyo. “Even at that age, we already had the confidence that we could rap better than anyone else,” says Chinza.

After graduating high school, Chinza started freestyling on the street with his friends. He took part in many emcee battles, where he got the reputation for his “alien” skills. In the battles, Chinza was able to change his flow at a moment’s notice, which often threw his opponent off balance.

“At first, I tried too hard to put lots of words in one verse,” says Chinza. “But as I did it more, I learned how to work with ‘time and space.’ I am not doing anything eccentric or strange. My skill is reading the situation and then not reading it, or not totally understanding it on purpose, to try to make myself and my audience feel good.”

Chinza’s rhymes are easy to listen to. Even when you don’t know what they mean, you can still feel that they are flowing naturally, as if his voice is more like an instrument. It’s this approach that sets Chinza apart from other Japanese rappers, perhaps similar in a way to U.S. alt-rock singer Beck’s stream-of- consciousness approach. All the songs on “100% rap,” consist of easy words that even children can understand, such as “mogu mogu” (“mumble”) and “ore wa rappa” (“I’m a rapper”).

“I don’t rhyme just to rhyme,” explains Chinza, who suddenly starts speaking quietly as if he’s letting me in on a secret. “I always try to make my flow sound smooth and comfortable, not putting too many words into it, but making full use of the sound of each word. But then it is always hard for me to adjust the meaning of the lyric to the sound.”

Chinza is in the middle of recording a new album of self-written tracks. He’s thinking of including a separate album to go with it consisting of remixes. That’s on top of another album he is working on with remixes of the songs from “100% rap.” He sees all this as just another direction, something that will enhance his style. He has also collaborated with breakbeat duo Hifana and delivers a classic performance on the track “Wake Up” from their new album “24H.”

At Summer Sonic, Chinza tried another experiment and performed with a group of backing musicians called the “Doping Band.” It wasn’t their first time playing together, but it is something that Chinza is still toying around with. He would stop and start the show frequently and changed from one song to another halfway through the performance, but the band didn’t fail to keep up and together they meshed in a way that was reminiscent of The Roots.

“Live performances are everything to me,” Chinza says. “Way before recording the album, I was already planning the concerts I’d do on tour. During recording, I was conscious that I was setting up the base for my live performance. When you perform live, you can alter your act according to the audience; and once everyone in the crowd has joined my party, I know I’ve done my job.”

Chinza Dopeness plays Kyoto’s Metro on Sept. 10; Bakuto Osaka on Sept. 19; Tokyo’s Womb on Sept. 24; and Oppa-La in Enoshima, Kanagawa Prefecture, on Sept. 26. For more information, visit www.chinzadopeness.com