How can I find a specific collation in pg_collation when using ICU?

Hello,

I tried to find a particular collation name in pg_collation, but I
cannot understand the naming convention after reading the following
article. Specifically, I want to find out whether there is some
collation equivalent to Japanese_CI_AS in SQL Server, which means
Japanese, case-insensitive, and accent sensitive. Could you tell me
how to do this? Is there any room to improve the PG manual?

https://www.postgresql.org/docs/devel/static/collation.html
--------------------------------------------------
23.2.2.2.2. ICU collations

With ICU, it is not sensible to enumerate all possible locale names.
ICU uses a particular naming system for locales, but there are many
more ways to name
a locale than there are actually distinct locales. (In fact, any
string will be accepted as a locale name.) See
http://userguide.icu-project.org/locale
for information on ICU locale naming.
--------------------------------------------------

Regards
MauMau