Well, I have no idea what you've been listening to, but if you haven't checked out The Blue Hearts, definitely do so. Some of the songs I like are "Linda Linda," "I Wanna a Kiss," "Train-Train," "An Endless Song," and "A Boy's Song." Beyond that, my standbys are Thee Michelle Gun Elephant ("G.W.D.," "Danny Go," "Gypsy Sunday"), The Pillows ("Hybrid Rainbow," Happy Bivouac," "I Think I Can"), and every once in a while, Ellegarden (lots of English songs, but check out "月"). A Japanese friend recently gave me some OreSkaBand, which is pretty catchy if you like the ska genre. Oh, and if you're interested in hip-hop, check out the old-school group, Schadaraparr.
My host sister sent me a mix CD a while ago, but because iTunes is evil, it didn't recognize any of the songs or artists. Because of that, I have a bunch of unnamed tracks which I've come to enjoy! I guess I should look up the lyrics somewhere...