Follow the arrow and the penguin. You're about to have a shopping experience with no comparison! Right off the escalator (the real store starts on the second floor), you'll see seasonal merchandise. Here are some yukata and jinbei. Jinbei are like pajamas with a loose robe top and shorts on bottom, though they are unisex.
Wow, the store packs a lot of different sections and distinct products. I wouldn't mind getting the life-size Ted ahahah it's really cute!