Type 99 "Last Ditch" used for homeland defense. Off the top of my head, I do not remember witch arsenal, but you can decode the symbols... I have never heard that they were ever issued to troops.
There is nothing wrong with the metallurgy, heat treating or anything else. They were simply made simpler using less material and quicker assembly procedures. They fire 7.7mm round which is the same bullet as the 303 British (.312 instead of .308 ).
Some bring-back's were reamed out to chamber a 30-06, but since the bullet is loose in the bore, they never worked all that well. Check yours to see if it will chamber a 30-06 by hand w/o bolt pressure ... Prolly not, since it looks all original
It's a bit beat up and it's not the most desirable of the Type 99's, but with a full Mum, the volley sight, the metal butt plate, it is a nice example. Later ones were even more crude down to rope sling and wooden butt plate, but still shot well. I suspect that if you scrub the bore and lube it up nicely, it'll shoot just fine. The bolt is super easy to disassemble and service. Just take your time and it will all be clear.
Please note, that the rifles were sighted-in at the arsenal and use the typical military sight picture of the time - the "6 O'Clock Hold" - meaning that using the peep, if you put the top point of the front sight on the belt buckle, you'll have a center mass hit.
These rifles with decent bores shoot around 2~3 inch groups at anything beyond 100m. They are nearly as powerful as an 06. They are certainly aimable out to hundreds of meters and lethal out to the limits of the sight, which on yours looks to 1,400m.
Ammo can be had from Mr Nambu or Graf & Son. It's usually about $1.25 a round now days. Brass is re-loadable. Do not shoot WW-II ammo, it's corrosive.
Be very careful of sanding the stock or messing with the metal finish. The Japanese used a lacquer substitute from a local plant that will raise a nasty itch if it gets on your skin. The split stock is not a defect, it's the wood drying out. They are two-piece stocks with a large dove-tail joining the pieces, and now old glue that has given up.
On the ones I have worked over, I tape the stock on both sides of, and flood the crack with CPES until it won't take any more. Then do the other side the next day. It freezes the split and bonds the two w/o altering the look. Once secure, they are shootable.
Here's more info:
http://members.shaw.ca/nambuworld/arisakas.htm
Have fun, and if you want to unload it, PM me