Have you seen t-shirts with Japanese words (especially kanji) online or at airports in Japan?
This kind of t-shirts are so popular in people who like Japan or people visiting Japan because those t-shirts are so cool and are wonderful gifts for their family and friends.
Words are written mainly in kanji and are varies: for instance, “一番 (Number One),” “夢 (Dream),” “愛 (Love),” and “友/友達 (Friends),” etc. Maybe you see those words as a tattoo on somebody’s body.
I totally agree that those are great gift. But sometimes there are impolite/dirty words, so be careful and ask the meaning before you buy.