KN^4

Let's hit the は行 for a look at words related to interest that might help make your 言い回し a bit more 日本人ぽい. We've got three for you today:

嵌る
はまる
hamaru

to get into (something in a big way); to fall into; to be addicted to; to
be deep into; to plunge into; to be deceived.

As you can see by the wide range of translations, 嵌る is all about something that TRAPS you. It can be as something that catches and holds your interest, in a 興味津々 way, like me and the song Paper Planes by M.I.A, or Brett and black tar heroin. Yes, 嵌る is the verb you use for drug or tobacco addictions as well.

流行る
はやる
hayaru

to come into fashion; to be trendy; to be popular.

"What's popular?" is a really common question in Japan. I always felt that there was a paradoxical tendency for the popular to be unpopular in America. I can't imagine the word "trendy" having a positive context. But kids in class will ask me, アメリカで、何が流行っていますか？ What's all the rage in America? And when some of my old students stopped by my house to say hi, they got into a conversation with Yuri who asked them which stars were popular among kids these days. Those kinds of topics come up a lot, and while me and my 調子乗っている, 考えすぎ ilk would never want to seem like our interests were pretty much the same as the national interest, I get the sense that this is no problem in Japan.

Another good word to associate with 流行っている、is ブーム。 As in "Dude, those butt toning sandals are so ブーム right now."

Confusing Example Sentence and Explanatory Video:

数年前、「ザ・ブーム」が流行っていたので、今でも「島唄」はカラオケの大人気な曲です。

惚れる
ほれる
horeru

to fall in love; to be charmed with; to lose one's heart to.

You can use 嵌る with 首っ丈, but 惚れる is a better choice. I actually only learned this word a few days ago, when my new students asked me if I had a girlfriend. When I said yes, they asked the same question Japanese people always ask:　どちから？Which one of you was the pursuer? I said it was mutual, and they said "惚れている？" which I replied "Yes" to, after figuring out what it meant. Then they asked "やっている？" and I turned bright red.

The most common usage I've come across on the webs is in describing someone as a 惚れる男 or a 惚れる女 (although men are much more prominent). It's basically the kind of person you could fall in love with.