夏恋★夏GAME by アンカフェ
 

I'm having trouble understanding certain parts of this song.

The very first line is this:
アゲる季節がやってきた

This would make sense to me if アゲる wasn't in there. What is アゲる季節?

夜もキメろ!!
Why is キメ written in kana? Is it related to キモイ?

I checked the lyrics. You've got the transcription correct. The rest of the surrounding lyrics are talking about an awesome summer (beach, blue skies, etc.). My guess is that it's 揚げる (either indicating it's a really hot summer) or 上げる (raise up/whatever).

The second one definitely needs context. The lyrics I found say "恋の季節さはじけましょう／ATAKKU 成功夜も極めろ" are the two lines. You got the transcription wrong. It's 極（きわ）めろ apparently.

Where did you find 成功夜も極めろ? All the lyrics I found for this song say キメろ. I tried to google "成功夜も極めろ" but didn't find anything.

You're right. I ended up on a page where a non-native had transcribed the lyrics. You got the lyric correct. アンティック珈琲店 夏恋★夏GAME 歌詞

Thanks. So if it's キメろ, what does 夜もキメろ mean?

アゲる is a fairly new slang word meaning "to raise one's spirits".

アゲる季節がやってきた means "The season to raise our spirits has come."

キメる is a slang word meaning "to be succesful" here. The other important meaning is "to wear (certain items) and look good".

夜もキメろ essentially means "Pick up a good one at night."

Whenever you see a word in katakana that you might expect to be in kanji, you are seeing a regular old word being used for a new slang meaning. This happens all the time.

決める = to decide
キメる = what I said above

上げる = to physically raise an object
アゲる = to upload, to raise one's spirits

Wow, I thought I knew what the slang words were. I have never heard of those. What you said about katakana slang words is helpful, thanks. Do you know of a good online website where I can learn all about the new slang words?

What does "pick up a good one at night," mean? Is that talking about picking up girls?

I don't know of a website unfortunately. I am a Japanese-speaker, so I just have not looked for one before. Perhaps other members know of some websites.

It means what you said. It's all about flirting. Summer is just considered the season for that kinda activity by many here.

Oh ok, thanks. What you said about katakana, there are other words in the song that are written in katakana: キミ, ハジけましょう, フリ, and トキメキ. Are these all slang words?

What does 一夜の恋も星になるさ mean?

Summer sounds like fun over there.

Here is a site with slang words, although there are gross words XD the list is pretty long a-o Japanese slangs (among young prople) dictionary Japanese slangs (among young people) E-Japanese.jp . Japanese study