Question: Susumu Ito was assigned to which Japanese-American part of the US Army Reserve?

Context paragraphs:
Michele S. Jones: Michele S. Jones was the first woman in the United States Army Reserve to reach the position of command sergeant major of the U.S. Army Reserve.  She was the first female non-commissioned officer to serve in the highest enlisted position of a component of the U.S. Army, active or reserve, and was at one time the highest-ranking African-American female enlisted person in any branch of the United States military, as well as the highest-ranking enlisted African American in the Army Reserve.

SIDPERS: Standard Installation and Division Personnel Reporting System (SIDPERS) was the main database or, rather, databases for personnel accounting by the United States Army.  The Active Army, US Army Reserve, and Army National Guard each had separate, largely incompatible databases, each bearing the name SIDPERS or a variation thereof.  RC-SIDPERS was nominally designed for both reserve components (Army Reserve and Army National Guard), but was further adapted for use by the National Guard, to create NG-SIDPERS.

Army Reserve Sustainment Command: The Army Reserve Sustainment Command (ARSC) is a subordinate command of the 377th Theater Sustainment Command.  The Army Reserve Sustainment Command is located in Birmingham, Alabama.  The command comprises five subordinate commands and has command and control of almost 750 Army Reserve Soldiers throughout the United States.  The United States Army Reserve Sustainment Command provides trained and ready Soldiers on a continuous and global basis to U.S. Army Materiel Command (AMC), the Assistant Secretary of the Army for Acquisition, Logistics and Technology (ASA(ALT)), the Defense Contract Management Agency (DCMA) and the Logistics Civil Augmentation Program (LOGCAP) in order to sustain Unified Land Operations.

Susumu Ito: He was in auto mechanic school when he was drafted into the military in 1940, two years before the Japanese attack on Pearl Harbor.  He worked as a mechanic, but was eventually assigned to the all Japanese-American 442nd Regimental Combat Team, which became the most decorated unit for its size and length of service in the U.S. Army during World War II.  He was an artillery spotter (forward field observer) assigned to C Battery.  He was promoted to the rank of second lieutenant on October 19, 1944.  Ito participated in the famous rescue of the "Lost Battalion", the first battalion of the 141st U.S. Infantry Regiment of the 36th Texas Division.  The action took place in the Vosges Mountains, in France, in October 1944.  Both units were attached to the Seventh U.S. Army.  The Lost Battalion had been cut off and surrounded by the Germans.  Lt. Ito was attached to I Company of the 442, which effected the rescue of the Lost Battalion.  Though the 442nd suffered extremely heavy casualties in the engagement, Ito emerged unscathed.  He was attached to I Company, of which only eight members survived this action.  Of the rescue, Ito later recalled, "Looking back, it wasn't an easy outing, but having come through it intact, it was an experience that cannot be forgotten or easily duplicated.  At the time, I thought that this was more or less a typical battle encounter with a strong enemy and not a special or unique mission.  I guess my analysis is not shared by history."  The U.S. Army later declared the Rescue of the Lost Battalion to be one of the top ten battles of the U.S. Army in its history.

416th Engineer Command (United States): The 416th Theater Engineer Command (TEC) is a United States Army Reserve unit that conducts theater-level engineer operations for US Army Central Command, US Army Southern Command, supports continental U.S. – based engineer requirements as directed, and is prepared to participate in Joint and Combined regional contingency operations.  It is also the higher command headquarters for the US Army Facility Engineer Group.

Permanent staff instructor: A permanent staff instructor (PSI) is a warrant officer class 2 (WO2), or senior non-commissioned officer (sergeant, staff sergeant or colour sergeant), of the Regular British Army who has been selected to instruct Army Reserve soldiers.  Each AR unit has several PSIs attached to it.  A normal rifle company in a Regular Army battalion has a single WO2, serving in the role of company sergeant major (CSM).  An Army Reserve rifle company normally has two WO2s.  One is the CSM, normally a part-time member of the Army Reserve, and the other is the seconded PSI, the only full-time member of the company.  The PSI is meant to provide the reserve company with the benefit of his professional experience, as well as to ensure that the training and operation of the company adheres to the Army's methods and standards.  The PSI is typically responsible for much of the company's administration work, and usually takes a particular role in the training of junior NCOs (corporals and lance-corporals, and equivalent).

81st Infantry Division (United States): The 81st Infantry Division ("Wildcat") was an infantry division of the United States Regular Army that was mobilized for service in both World War I and World War II.  The division was inactivated in 1965 and reactivated as the 81st Army Reserve Command (ARCOM) 1967.  During that time, the 81st ARCOM was responsible for deploying US Army Reserve units to Vietnam, Southwest Asia, and the Balkans.  The 81st was redesignated in 1996 as the 81st Regional Support Command (RSC) and is responsible for all Army Reserve units in the southeast United States and Puerto Rico.

442nd Infantry Regiment (United States): The 442nd Regimental Combat Team is an infantry regiment of the United States Army, part of the Army Reserve.  The regiment was a fighting unit composed almost entirely of American soldiers of Japanese ancestry (mostly from Hawaii) who fought in World War II.  Most of the families of mainland Japanese Americans were confined to internment camps in the United States interior.  Beginning in 1944, the regiment fought primarily in Europe during World War II, in particular Italy, southern France, and Germany.

Mari K. Eder: 'Major General Mari K. Eder is a retired United States Army Major General.  General Eder was appointed Commanding General of the United States Army Reserve Joint and Special Troops Support Command (redesignated as the 76th Operational Reserve Command in 2013), Salt Lake City, Utah, in October 2009, retiring from the Army in 2012.  Prior to assuming command of the USAR Joint and Special Troop Support Command, she was assigned as the Deputy Chief of the US Army Reserve.

Office of the Chief, Army Reserve: The Office of the Chief, Army Reserve (OCAR) is located at Fort Belvoir, VA, and provides the Chief, Army Reserve (CAR) with a staff of functional advisors who develop and execute Army Reserve plans, policies and programs, plus administer Army Reserve personnel, operations and funding.  The CAR is responsible for plans, policies and programs affecting all Army Reserve Soldiers, including those who report directly to the Army.  OCAR is made up of specialized groups that advise and support the CAR on a wide variety of issues.

Supporting paragraphs: Susumu Ito 442nd Infantry Regiment (United States)
Answer: 442nd Regimental Combat Team