Translation Request Thank You in advance.

[Gunbatsu]

[Nick Komiya]

It's a navy name tag for someone named Sakura with Blood Type O. According to the back side he seemed to belong to a unit having Yokosuka as home base.
The unit's ID code is ウ623. I don't research navy matters, so I do not have the code book, but perhaps someone here has the book shown below, and can look it up.
However, what I'm not sure of is whether the backside writing is only from a addressed postcard scavenged as stiffener backing for the tag or whether it was written after the tag was made.

[Gunbatsu]

Thank You Nick for the helpful translation. I really greatly appreciate it

[adachi]

According to the list of IJN unit ID codes U623 as well as U624 and U625 are unassigned. Maybe the book Nick suggested has more info archives don't have but I'm referencing a 1946 dated 2nd demobilization bureau document so I'm inclined to believe it.

[Nick Komiya]

ウ６２３ was indeed an assigned number to a unit at Yokosuka, as seen used in this postcard sent home from a member of U623. You need the book.

[adachi]

ウ６２３ was indeed an assigned number to a unit at Yokosuka, as seen used in this postcard sent home from a member of U623. You need the book.

Unfortunately that book is sold out everywhere and as I said primary sources showing compiled by the navy after the war show nothing for U623. Thanks to the evidence you posted at least we know there was something, but it was probably a unit formed in the final days of the war, and either slipped through the cracks or was not deemed significant enough (ie never fully activated) to be put on the list. With that being said, there's a good chance Onishi's postal book doesn't have the unit either, unless he is in possession of some magic treasure trove of extra IJN postal code information that has somehow evaded both the US authorities gathering intel during the occupation and all Japanese archives afterwards.

JACAR Ref.C16120718600 - IJN Unit Postal Code Chart (Pt.1) - 2nd Demobilization Bureau (former IJN ministry), February 19th, 1946

[Nick Komiya]

The tricky thing about the navy's unit postal code system was that the same code was often assigned to different units on an annual basis or suddenly ceased to be used and then be reassigned again.

The problem with relying on postwar lists done for facilitating repatriation was that these only show latest codes as issued on 19th July 1945, but before that, was a June 1944 list, May 1943 list, Jan. 1942 list and April 1941 list.

A number assigned to unit A in 1941 could show up as unassigned in 1942 and get reassigned to unit B in 1943, though the majority did stay constant.

The reason why that 2003 book has nearly 400 pages is, because it tracks unit codes throughout all known annual lists. There was also a 1981 book by a different author, but that one cost as double as much.

[Nick Komiya]

Missed it by a hair. No success in pinning the unit down, but unit code U623 would have been given out between May 10th and 25th of 1945. As seen below, the full range of unit numbers from U605 to U622 were assigned on 10th May 1945, of which U617 to 622 were all construction units, the IJN's equivalent of the Seabees, mostly Gunzoku, by this time, involved in moving military production facilities underground.

Later that month, on the 25th, U635 to 637 were given out to NLF units in Maizuru, so assignment of U623 would have been within the 2-week blank period I haven't been able to fill.