AtagoSounds currently sell music royalty in AudioJungle and AudioStock.

AudioJungle
AudioStock (English Guide)

They are companies that sell royalty music license to use it for video works and events etc in Australia and Japan.

Registration of music

Regarding music registration, AudioStock seems not to be so difficult at the moment.

Although they check unnecessary noises strictly, if you upload the music for commercial use, video use with being careful there, it will be approved about 1 week later and will be on sale.
To register a composer you need a bank account in Japan.

Basically AudioJungle is also the same flow, however the registration review is getting harder and harder.

We can see the post on the forum that ask advices of rejected tracks on Envato forum, but sometimes it seems to have enough quality.

Receiving sales

You can get paid of a certain percentage of sales.

AudioStock will transfer to the bank account.

AudioJungle will pay via PayPal, Payoneer, Skrill or SWIFT, so you don’t have to have the bank account in US or Australia.
But you have to declare AudioJungle your tax number, otherwise you have to pay high tax.

Market size

Currently (27/March/2017),
AudioJungle has 499424 songs and AudioStock has 33895 songs in their library.
There is huge deference.

I can say it’s a valid deference because of their market size, AudioStock is mainly focus on Japan, and AudioJungle develops global.
Moreover the difference of the market size would be more than deference of the number of songs.

Musical feature

Sometimes I feel that Japanese general advertisement music tendency is quite different with world standard.

For instance, the catchy chord progression which is used in Japanese pop songs would be said “oriental chord”.

Current Japanese composers tend to use many modulate change and complex chord progression in a song.

In contrast, the American and European composers tend to make amount of information from intonation of musical stuff.

We can see this deference at the library of AudioJungle and AudioStock.

These are both of my library. I believe you can see my separate creation.