I don't have any specific information about "Sky Angel Vol.137" as it could refer to various things, such as a manga, anime, or other media franchise. Without more context, I can only provide some general information:

"Sky Angel" is not a widely known title, so it's likely a niche series or publication. Volumes in the teens and 20s are common for manga and anime, but reaching into the triple digits is unusual.

If this is a manga or anime:

- It would be quite long-running, with over 100 volumes published.

- Volume 137 suggests it's still being produced or has been popular for many years.

If you have more details about what type of media this is or what language it's in, I may be able to provide more specific information or help you find relevant content. Otherwise, you might want to check official sources or retailers for accurate information about this particular volume.