If you didn’t know any better and went to a concert by Osaka, Japan rockers Shonen Knife — like, say, this Wednesday at Mayday (4227 Spring Grove Ave., Northside) — and someone told you the band is celebrating its 30th anniversary, you’d probably slap them and tell them to apologize to the three women in the band for suggesting they’re any older than about 25. The trio’s youthful energy and adrenalized Pop Punk (not to mention some spectacular genes) suggest it’s the work of three twenty-somethings, with the great, catchy songwriting and air-tight performances the only hints that Shonen Knife has been rocking audiences around the world for the past three decades.The MidPoint Music Festival alums are one of the most beloved Japanese exports since Hello Kitty and their latest album is a tribute to the group’s biggest influence, The Ramones. Shonen Knife’s Ramones cover album Osaka Ramones is named after a tribute side-project of the band members’, but it could also be Shonen Knife’s nickname. Like The Ramones, the Japanese Rock legends’ trailblazing is undeniable. Doors open at 8 p.m. and the show is a rare ticketed event for Mayday — admission is $8. Local Noise/Punk crew Weakness opens.