In English, “cute”. If you came to Japan with zero language study beforehand, this is one of the first words you would pick up.
Unless you’ve prepared yourself mentally before coming to Japan, the overflowing element of cuteness can be disturbing. Like being hit in the head repeatedly with a life-size alligator pillow by a laughing third-grader in school uniform and pigtails. Weird, but you get used to it after a while.
Japan is a society that thrives on cute. It defines fashion, trends, styles, and invades every possible space. A cell phone is not complete without some fuzzy animal or character attached to it. Announcements in a store or at the station are not correct unless they are given in a high, nasal, bouncy feminine voice. (It starts to sound like the same person after a while, much like movie trailers in America almost always use the same narrator.)
But, like caffeine (and I’m thinking caffeine from the coffee at Mister Donut, where a particular employee has a natural voice that is shockingly high-pitched and nasal), the effect eventually wears off, so I don’t notice it as much anymore. Which is probably why the cuteness—or kawaii-ness—of Japan continues, and even escalates. Cute value is shock value, and when the shock wears off, the only answer for businesses trying to attract more customers is to step up the cute. So DoCoMo (the cell phone company) gets a Super Mario-esque mushroom with spindly arms and legs as a mascot, and (last year’s big hit) a pair of girls singing a repetitive, fluffy song is recruited to sell a tarako (cod roe) product. (That particular song has no redeeming quality, but it’s the sticks-in-your-head type, so it made it into the top 10 for a brief time.)