REDONDO BEACH, Calif. -- Rishi Sharma has always been into superheroes – the real kind. That's why, as a junior in high school, he made it his mission to meet as many World War II combat veterans as possible.

"I ditched so many days of high school to go do an interview," he said. "I started riding my bike to the local senior home. I interviewed those guys. Then I started driving."

It became a daily undertaking. When we first met Rishi in 2016, he was driving all over Southern California, interviewing guys like Marine tank commander Ernie Eisley.

Rishi, 20, talks to the men for hours, then gives the recordings to their families. He says he does it because time is short. We're losing about 400 World War II vets a day.

Rishi Sharma interviewing Ernie Eisley. CBS News

"It's amazing how much history and knowledge is encased in each one of these individuals and how much is lost when one of them dies without sharing their story," Rishi said. "The fact is I wake up every day to obituaries, guys who I wanted to interview and I have to find out they died."

Rishi doesn't come from a military family. His parents immigrated here from India, and yet, he cares as much about our greatest generation as anyone I've ever met. In addition to his in-person interviews, he telephones at least five World War II vets a day, just to thank them for their service and sacrifice.

"It means a great deal to me that you were willing to endure all that so that I could be here today," Rishi told one vet on the phone.

Rishi Sharma (R) has been on a mission to meet World War II veterans and interview them. CBS News

After this story first aired, Rishi raised enough money on GoFundMe to expand his mission across the country. He travels by car-and often sleeps in it. So far, he has interviewed over 850 vets in 40 states -- learning about their stories and their scars. Those that have healed and those that will never.

It's nice to know that as long as there are World War II veterans willing to talk, there will be at least one young man willing to listen.