VAN HALEN frontman David Lee Roth attended the April 20 concert in Tokyo, Japan by NATURALLY 7, an American music group with a distinct a cappella style they call "vocal play." Roth visited NATURALLY 7 backstage and joined them in singing "Happy". Check out video footage below.According to The Pulse Of Radio, Roth has said in the latest installment of his web series, "The Roth Show", that VAN HALEN is working on some kind of "secret' project. Roth said on the show, "Doing some catching up here, a little bit of a scrapbook. We've been doing a lot of traveling. [I've been] working on a great VAN HALEN project — can't announce anything or I'd have to come find you and swear you to secrecy." VAN HALEN has been mostly silent since coming off the road in summer 2012 and canceling a large portion of its touring plans behind that year's album, "A Different Kind Of Truth". The band — which reunited with Roth in 2007 after 23 years apart — has reportedly been working on its 13th studio album. Roth said in an interview late last year that VAN HALEN had started work on a new record, revealing, "I write lyrics routinely and the band plays together routinely, at least three times a week up at Ed's [Van Halen] place." "A Different Kind Of Truth" sold 187,000 copies in the United States in its first week of release to land at position No. 2 on The Billboard 200 chart. The CD was is the band's first full-length offering with David Lee Roth since "1984" was released in January 1984. Roth exited the group in 1985, a year after its "1984" album was released.