Here is a short description of what the 200th did at Toungoo, based on the Chinese sources at
I have done a synopsis in English below. Don't have a good enough map, so I am not able to translate the names of local villages etc.
Advanced elements of the 200th Division arrived at Toungoo on March 8, 1942 and took over defensive positions from the British forces. The disposition of the Chinese forces were as follows: Toungoo itself would be the main defensive position, with outpost at鄂克春. The cavalry regiment plus a company of infantry pushed up to River彪关, with a platoon of cyclists taking up position near the bridge over the river.
Japanese troops from the 143rd Regiment of the 55th Division advanced right up to the bridge on the 18th, but was ambushed and withdrew. After night fell, the Japanese continued their attacks with small units, and the Chinese covering force withdrew. 彪关 fell on the 19th.
On March 20, the 143rd Regiment plus cavalry units attacked the positions of the Chinese Cavalry Regiment north of River彪关, driving the Chinese forces back with heavy losses. The bulk of the regiment were withdrawn to the north of Toungoo, leaving only a company of cavalry and infantry each to delay the advancing Japanese. On March 21, Japanese forces brushed aside the delaying forces and reached the divisional outposts at 鄂克春.
The 122nd Regiment of the 55th Division attacked Chinese positions at first light on March 22, but made little headway. On March 23, the Japanese tried again with strong artillery and air support, but was once again rebuffed, leading them to note that this was the first time they met with determined resistance in Burma. On March 24, with the 122nd Regiment making frontal attacks, the 143rd Regiment with the aid of the locals was able to make a surprise attack on the airfield about 6 km northwest of Toungoo. The airfield was only lightly defended by an engineer battalion, and the commander panicked and withdrew hastily. Now the 200th Division was encircled on three sides with its main communication route cut. Faced with this situation, the Chinese abandoned the outlying positions to concentrate their defence near the city walls of Toungoo.
On March 25 the Japanese launched an all out attack with the 143rd Regiment on the left, the 112th Regiment on the right, and the Cavalry Regiment plus a company of infantry ordered to attack along the R. Sittang valley. The objective was to press the Chinese forces against R. Sittang where it would be annihilated. Despite local penetrations in the north-western part of the defensive perimeter, no major progress was made due to heavy Chinese resistance. Japanese attacks continued on March 26 and by the evening, the Japanese had taken the western part of the city to the west of the railroad while the Chinese troops held on to the main part of the city east of the railroad.
On March 27, the Japanese continued to press their attacks with air support, and in the afternoon fired large numbers of tear gas shells. Despite all this, the Chinese held their ground. On March 28, the 3rd Heavy Field Artillery Regiment attached to the 55th Division arrived, and with strong support from bombers and more gas attacks inflicted heavy casualties on the Chinese, who still managed to stand their ground. At the same time, leading elements of the Japanese 56th Division consisting of a company each of infantry, machine gunners and field artillery arrived in 45 trucks to reinforce the attacking Japanese forces. This force crossed the R. Sittang and moved rapidly northward, attacking the 200th Divisional HQ on the high grounds near 阿列米扬 and reaching the bridge spanning the R. Sittang on the eastern edge of Toungoo.
On March 30, this force, after 3 hours of heavy fighting, broke out of the bridgehead and reached the eastern outskirts of the city. Meanwhile, the assaults of the 55th Division within the city itself continued without much success. Unknown to the Japanese, the bulk of the Chinese forces had already started their withdrawal on March 29, and the troops covering the withdrawal did their job so well that the entire division were able to retreat in good condition, taking all the wounded along.
I believe there is also a description of this battle in the Senshi Sosho ...