12-gun machine-gun company was usually assigned to infantry battalion of Type "A" infantry regiments and similar divisions, like Counter-attack division of 1945, as shown here.
Note, this version of TO&E has 2 NCOs, whose assignments not clear from the organization details or TO&E notes. So their assignment is my guesstimate.
8-gun machine-gun company like shown here was the most widespread MG company organization of the IJA infantry.
Note, that company warrant officer commanded ammunition platoon, which put additional burden on the company master sergeant, who had to do most administrative work by himself.
Another strangeness of this TO&E is, that 4 MG platoons were served by only 3 ammunition squads of uneven strength.
“Ocean” (海洋) or “Regimental Combat Team” divisions were created in 1943-44 for the defense of small islands and atolls in the Pacific Ocean. Its infantry was organized into de facto company groups with organic heavy weapons support. Infantry regiments were also made self-contained, so divisional support units were reduced.
Those divisions had two types of infantry regiments: “coast defense” for static defense and “amphibious” (which had its own amphibious transport in form of landing barges and boats) for local counter-attacks.
Infantry company of the amphibious infantry regiment is shown on drawing below. Infantry company of the coast defense infantry regiment had neither anti-tank rifle nor mortar platoon.
On 28 February 1945 Imperial Japanese Army introduced new TO&Es for the divisions to be formed for the Homeland defense.
Type 1
infantry regiments were for the "Coastal Deployment Divisions" (沿岸配備師団) to defend the coastline proper (Type 2 infantry regiments were to be
formed for the "Mobile Striking Divisions" (機動打撃師団),
intended to counter-attack US forces, that landed on the Japanese Islands).
For static coast
defense firepower was preferred over maneuverability. Each infantry company had
6 machine guns and 2 battalion guns – on par with some Japanese infantry
battalions. Each of first three infantry battalions of Type 1 infantry regiment
had 3 such companies and 1 infantry gun company (armed with any guns IJA could find,
including old tank guns, installed in tank turrets).
But
Japanese refused to abandon the ground rule of their tactics, that defense must
be active. That’s why they’ve created smaller assault company for local
counter-attacks against landings. Each of first three infantry battalions of
Type 1 infantry regiment received 1 assault company, while fourth battalion of
the regiment was entirely composed of 3 such companies.
Squad
organization of those companies was different from the standard IJA infantry
organization.
First of
all, in 1945 the Infantry Training Inspectorate published "Infantry Combat
Training", which officially introduced the so-called "group
tactics". Now rifle squads were to be made up of groups with its own
designated leaders. Also grenade discharger groups now could be attached to the
rifle squads, which was not allowed before.
Second,
squads in companies of Type 1 infantry regiments were smaller, then standard
IJA infantry squads. Compared to standard 13-men squad assault companies had
only 10 men in squads, while infantry companies had only 7 men (TO&E note
prescribed 8 men and 7 rifles in each rifles squad, but detailed organization
research shows such number of men was impossible to maintain while such number
of rifles was simply unavailable in TO&E).
Third, rifle
squad of assault company was unique, as it had no LMG, but instead had SMG and
grenade discharger. And from the TO&E it seems, that IJA still treated SMG
as “mini-LMG”, because it was not just crewed with LMG-men, but there were 2 of
them – so SMG wasn’t personal, but crew-served weapon.
