In September 1942, Warrant Officer Ota and FCPO Shiro Sakai served as pilots on the seaplane tender Kunikawa Maru .

The Kunikawa Maru departed Truk on 8 September 1942 with an air group of six F1M Pete floatplanes. It was carrying materials and personnel to begin construction of an airfield at Buin in southern Bougainville. After leaving the Shortlands on 10 September it was also tasked with scouting locations in the Solomons suitable for use as forward seaplane bases.

On 11 September 1942, PBY 11-P-10 from VP-11 was flying a search patrol from Ndeni when it was shot down at 09:30 east of Malaita. IT had been shot down by a pair of Pete floatplanes from the Kunikawa Maru flown by Warrant Officer Ota and FCPO Shiro Sakai. Both pilots were jointly credited with the flying boat as the unit’s first combat kill.
The eight-man PBY crew under Lieutenant Carlton H Clark was collected by the destroyer Murasame and then transferred to the cruiser Atago the following day. The crew were eventually transported to Japan where two of the crew died as POWs, with the remainder eventually liberated from the Shinjuku POW camp near Tokyo.

A strike group departed Henderson Field, Guadalcanal, at 02:45 on 5 October to attack Rekata Bay at dawn. This group comprised of eleven SBDs and five TBFs, but due to the bad weather only six SBDs and three TBFs reached the target area in scattered groups. The attack was led by Lieutenant Commander John Eldridge of VS-71, and escort was provided by four VF-5 F4Fs. From 05:30 the SBDs dropped 500-pound (227kg) bombs and strafed targets both on the water and ashore.
Three F1M Petes (two from Kunikawa Maru and one from Sanyo Maru) had arrived at Rekata Bay the evening before to provide CAP for retreating Tokyo Express destroyers. These three were taking off just as the first SBDs arrived. An SBD attacked Warrant Officer Ota from behind, and his gunner exchanged fire with it. However, the explosion from a bomb dropped by the SBD unbalanced the Pete, causing it to crash back into the water. Both crewmen were injured, and after rescue by natives in canoes they were medically evacuated.
Meanwhile the two other Petes got airborne and chased an SBD. Their attacks damaged it so badly they left it to its fate, and instead pursued a TBF but it proved too fast for them.
The damaged SBD was that flown by Lieutenant Commander Eldridge. It had been hit in the engine which began malfunctioning. Eldridge nursed the aircraft as far as the southern tip of Santa Isabel where he lost oil pressure and made a forced landing. Fortunately, Eldridge and his rear gunner were uninjured and were found by friendly natives. They were picked up by a J2F Duck amphibian on 8 October which returned them to Henderson Field.

Ota ended the war with 1 shared biplane victory.

Claims:

Kill no.	Date	Time	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1942
	11/09/42	09:30	1/2	PBY (a)	Shared destroyed	F1M		E Malaita	Kamikawa Maru

Biplane victories: 1 shared destroyed.
TOTAL: 1 shared destroyed.
(a) PBY 11-P-10 from VP-11 shot down with Lieutenant Carlton H Clark and crew becoming POWs.

Sources:
Solomons Air War Volume 1: Guadalcanal August - September 1942 - Michael John Claringbould and Peter Ingman, 2023 Avonmore Books, ISBN 978-0-6452469-3-3
Solomons Air War Volume 2: Guadalcanal & Santa Cruz October 1942 - Michael John Claringbould and Peter Ingman. 2023 Avonmore Books, ISBN 978-0-645-70045-9