I'm trying to take immersion to the max so i figured a topic where people post recommendations about their favorite Japanese bands would be really helpful.
I listen to J-music while I'm doing other things through the day just to always have some Japanese exposure.

The best stuff is the low beat songs where you can really hear the words and follow along/repeat(sometimes).

Here is what I've got so far:

Sakanaction: really relaxed chill music i love how i can completely hear every word they are singing.

School Food Punishment: This was recommended to me in another thread and I REALLY like it. The music is much better then the name sounds you have to try it.

Rip slyme: Another recommendation, I'm not really into this one because it is difficult to hear the words and follow along.

I'm really into the laid back, chill type of songs, kind of like the closing to anime most of the time

So post the name of the group and what style of music they play. Hopefully everyone will find something that they like
Also post what type of music you like so there can be better recommendations

If you like J-pop, then there is the one and only Salyu:

Also this is nice -another J-pop band, altough not with a vocalist
as striking as the previous, but quite easy on the eyes:

Speaking of easy on the eyes, but at the absolute goddess
gorgeous level: Miki Imai:

Watch her and tell me she's not the best looking woman you've ever seen!

How about Enka?

It's very slow and the words are easy to hear.
It makes for good listening practice.

I like Moriyama Aiko (

)
and カレン (

).

Both are young, beautiful and have great voices.

this amazing live performance of yami n furu ame by shiina ringo

and I love the song that ayumi hamasaki sings in this cm lol

here's a couple of slower-paced, chill songs i like. mostly rock/pop. they should be easy to follow.

FLIP -茜

and a few more because FLIP is just that awesome:
す・て・き Reaction Darts it's a lie ライラ (live) Butterfly (live)

Heavenstamp - Morning Glow

Utada Hikaru - Stay Gold

Kamiki Aya - walking down the street

male:

D'espairs Ray - 闇に降る奇跡 (classical white)

Karasu - 黒髪ストレンジャー

lynch - Quarter Life

Miyavi - Selfish Love

Sadie - Ice Romancer

MUCC - ココロノナイマチ

Dir En Grey - 鼓動

D'espairs Ray - Paradox 5

...and a lot more but i'll stop here

I've got an account on last.fm which is kinda like a certain more popular site that I forget the name of, but it's, you know, 'personalized radio', matching new song suggestions based on other people's preferences, etc. Anyways, last.fm has a -lot- of Jpop (and some Enka, which I've mostly allowed to stay in my playlist). So basically I just listen to that, although it sort of fails at being complete immersion because I just can't bring myself to delete some of the Shonen Knife and BoA songs that are in English... but mostly it's my own Japanese music channel.

(That other site may also work now, it was several years ago that I found they didn't have any noticeable amount of Japanese music.)

Oh, and you can also actually listen to the radio from Japan:
http://www.simulradio.jp/

A lot of stations have a fair bit of English lyric music in the mix, both what you'd hear in America as well as Japanese artists singing in English.

Hamasaki Ayumi
Perfume
Every little thing
AKB48

Best ones in some sort of descending order, after much searching.

ミスチル (Mr. Children)
サリュ (Salyu)
Radwimps
Bank Band
Ellegarden
Greeeen
月子天野 (Amano Tsukiko)

I'm sorry i have such an issue with most j-music. they are really reluctant to just jam, and always come back to either some version of happy music, which I can't stand, or else pithy sentimental stuff. it's like japan is having their 80's moment now, and there's all this product out there, (which means people are buying it) that is exaggeratedly sentimental and really ripping off a lot of 80s rock tropes that we would groan at over here. (even sakanaktion is super guilty of this and I love them regardless).

anyways I just wanted to say thanks for the heavenstamp, lynch and FLiP recs, they are pretty sweet. cheers...

http://www.simulradio.jp/ is priceless. Thanks.

Music I can recommend: X-Japan, Do as infinity, Every Little Thing, Hide, The BAck Horn, B'z, Boowie, Aikawa Nanase, The Brilliant Green, Kiyoharu, Globe, Ozaki Yutaka, Yuzu, Shiina Ringo, Glay, Kana, Luna Sea, Bump of Chicken, The Pillows, The Blue Hearts to be continued endlessly... Immersion staato.

Prefacing this by saying I probably have terrible taste in Japanese music. I wouldn't know, but I have a feeling it would be comparable to some random Japanese kid thinking Britney Spears is great music lol.

I mostly like faster songs with some cool guitar, drums, and bass. Not so much a fan of slower music.

Scandal:

Doll -

Anata ga Mawaru-

Shojo S - billions of videos due to being a Bleach OP.

Heavenstamp:

keikei recommended them already and I wanted to second that recommendation. Not too many lyrics for some of their songs though.

Hype (remix) -

Kyary pamyu pamyu:

Ponponpon -

I can not explain why anyone likes this song, but it freaking grows on you. It's so... bubbly happy.

Theatre Brook:

Uragiri no yuuyake -

Durarara fans would recognize this. If anyone knows other bands with a similar sound to Theatre Brook, let me know cause they rock.

I just thought I'd post a link to this site I found, which is really good for finding music videos from obscure groups: http://sparkplugged.net/

The Back Horn's 夢の花 (Yume no Hana) --

Acidman's 赤橙 (Sekitou) --

They play rock mostly but have some chill songs like these as well.

the new sdn48 new single is hilarious

aobouzu

tokyo jihen singin a cover of the song c'mon let's go

cover of this catchy dorlis song cause dorlis's version ain' ton youtube

I absolutely love Tokyo Jihen. Not really chill or downtempo, but still I think they're worth checking out. The lyrics are usually relatively easy to catch, although sometimes the text itself is rather difficult.

Here's possibly my favourite song, "Sounan"

"Yume no ato" is softer and slower and you'll probably like it more

Have you heard of "Mouse on the Keys"?
They tend to play in a style known as "math rock".
It is instrumental music (no singing).

It is music for random breaks, stops, and changes.
Almost like a computer if it played random beats.

Here's the best example of their style IMHO:

The title is Saigo no Bansan which translated to "The Last Supper" (yes, that Last Supper).

Rin Toshite Sigureare by far my favourite band right now, the bands that follow close behind are: WEAVER, flumpool and One ok rock. Honorable mentions go to the telephones, the WORLD (those deathnote intro guys), Genki Sudo, Kyu Sakamoto, Scandal and The Pillows.