Sakura blossoms, shrines, watching the first sun rise of the new year, making
mochi with a mallet, dressing up in traditional or formal japanese clothing, the castles
On the food side: udon, takoyaki, nikujaga, tonkatsu, shabushabu, sukiyaki, ramen, sushi, okonomiyaki (not my favorite but others seemed to like it)
If you can find a dessert called yukino ichogo (I think that's what it was called), eat up. Kind of a strawberry shortcake. At least my 20 year old self loved those things. Also buy a hot yakimo sometime from a vendor that bikes around