Kassim performs with the DMV Hip Hop Orchestra at the National Postal Museum next week. (Yusuf Kazmi)

It’s 6 p.m. on a Tuesday, and Kassim Okusaga is ready to leave his job at the Holiday Inn near Capitol Hill — not just for the evening, but for good. The 25-year-old calls his job as a front desk agent a “side gig,” as he pursues a career as a rapper best known by his first name.

He has yet to release a full-length solo project, but a series of singles, videos, live shows and collaborative projects with his crew 20NVR have earned Kassim the attention of such bigger name artists as Joey Purp and Tyler, the Creator. The Prince George’s County native hopes it’s all leading to something huge.

“Hopefully, I’ll only have to work at the hotel for a couple more months,” he says. “They know it, I tell them all the time. I’m very honest.”

Honesty is at the core of Kassim’s lyrics, all of which he writes without the use of a pen, paper or notes. Instead, he records ideas for melodies and verses on his phone’s voice memo app and plays them while driving or brushing his teeth — and by the time he gets to the studio, Kassim has an entire song memorized. It’s a skill he picked up while reading Jay-Z’s memoir “Decoded,” which describes how he learned to memorize rhymes as a drug dealer who spent hours on street corners. Kassim did the same thing while working at McDonald’s as a teen; he’d rap over Marvin Gaye or Stevie Wonder songs that came on the radio during his shift in the kitchen.

Kassim’s lyrics resound with a sense of overcoming roadblocks. He writes about his friends who’ve died, about witnessing his parents’ tumultuous relationship when he was a kid, and about his late Nigerian grandmother, who only knew one phrase in English: “I love you,” her last words to Kassim. He raps with soul over jazz-sampling beats about how he battled suicidal thoughts and an alcohol dependency while attending Towson University. He doesn’t remember that time fondly.

“There were times I was drinking and driving, or times I pulled up to parties and just threw up,” he says. “I was drunk texting people, raging. It was a lot.”

After his cousin was killed by a drunk driver, Kassim finally sought the help he needed with therapy sessions that helped him refocus on school and, of course, his music. Around this time, Kassim got involved with the DMV Hip Hop Orchestra, a rotating cast of about 15 musicians who use classical instruments to give rap songs a new life. When the orchestra visited Towson in 2015, founder Marcus Moody asked if anyone in the crowd wanted to get onstage and rap. All five of the 20NVR members raised their hands, including Kassim.

“We hit a stride that gave me goose bumps, just from freestyling,” Moody says. “That magic grew and set the precedent for where we are today.”

Kassim’s energetic but thoughtful lyrics complemented the full sound of the orchestra. “I was tired of hearing repetitive rap songs without moving strings parts, and I was tired of hearing moving strings parts without hard rap lyrics,” Moody says. “The whole goal of the orchestra is to encourage collaboration with people who would never otherwise meet. I think there’s a craving for something genreless, or a new genre. At the core of everything, it’s really the soul. And once you put a lot of people in a room who have a bunch of soul, all that other stuff doesn’t matter.”

Kassim felt the connection, too: “Some days I like trap, some days I like the club bangers, and some days I like pop, but soul is definitely the essence of who I am.”

With Kassim’s help, the orchestra started drawing audiences to shows at the Kennedy Center, the National Arboretum and Afropunk festival. Robust string, rhythm and horn sections back vocalists, who transition from covers of classics like Pete Rock and CL Smooth’s “They Reminisce Over You” to such modern hits as Chance the Rapper’s “No Problem.” On March 7, the orchestra will perform a set of original songs, including a handful by Kassim, at the National Postal Museum in honor of the 20th anniversary of the Hip Hop Culture stamp.

With a full orchestra behind him, Kassim has nothing but confidence now. He already has an award speech prepared, you know, just in case — as he raps in one of his songs, “still owe my granny a Grammy.”

Kassim knows a red carpet invite doesn’t just come to any rapper who dreams of getting there. That’s why he watches documentaries about how albums like Jay-Z’s “Reasonable Doubt” were made and reads books by Pharrell. It’s why he spends most of his free time at the studio or practicing for shows, and why he still wears the bracelet he got from Tyler, the Creator as a guest to his music festival in 2017. Though he was star-struck, it was the first time Kassim really thought of himself as a musician with fans of his own.

“You can’t tell me where you’re going if you don’t know where you’ve been,” he says, looking down at the bracelet. “So, I have nothing but pride when it comes to who I am today.”

If you go

Hip Hop Culture Block Party

Thursday at 6 p.m. at the Smithsonian National Postal Museum, 2 Massachusetts Ave. NE. postalmuseum.si.edu. Free.