Round 5 begins!
Round 5's theme is Leap Year*! That's right, we're celebrating that odd once-every-four-years day of February 29th. Sure, you don't get the day off or have any parades (although if your birthday is the 29th, you finally get to celebrate on the day itself) -- but it's a rare enough event to get at least a little more notice.
Because Leap Year tends to be symbolized by a frog, this round your wallpaper must feature artwork from the series Keroro Gunsou (Sgt. Frog) and contain at least one (1) of the frogs. Any and all styles of wallpapers are accepted; the wall can use official manga or anime artwork, professional doujinshi from the series or your own drawings for the show. You can submit as many wallpapers as you like; you have 1 month in which to do so (see the Events Calendar for dates). Be sure to include the which?waller round 5 signature in the bottom of your wall.

Good luck, wallers!

*Note: This would have made more sense if I had kept to the original schedule, in which Round 5 was supposed to start March 1. Oh well.

so as long as it contains a frog from Keroro it's okay? Like, the main focus doesn't have to be the frog, it can be a crossover or something

Crossovers are acceptable.

is it okay if I only include part of the frog? (like crop off the head or something)

No, you need to include the whole frog (or at most, trim off a bit of an arm or a leg if they're off to one side.)