From this site:

Nihon Kaigun

and this page:

Imperial Submarines

"12 May 1944:
N of Buka Island. The I-176 is spotted by an American patrol plane and her position is signaled to DesDiv 94 in the Treasury Islands. Cdr J. A. Nevins, ComDesDiv 94, steams out of the Treasuries to hunt the submarine with Cdr N. A. Lidstone's USS FRANKS (DD-554), Cdr D. A. Harris' HAGGARD (DD-555), Cdr P. H. Brady's HAILEY (DD-556) and Cdr E. E. Evans' (later MOH/Posth) JOHNSTON (DD-557).
16 May 1944:
East of New Ireland, near Buka Island. DesDiv 94 is steaming in scouting line. The HAGGARD makes a sonar contact on her starboard bow at a range of 2,800 yards. The destroyers keep the submarine down for about 20 hours. The HAGGARD, FRANKS and the JOHNSTON make five separate attacks. The HAGGARD suffers slight damage from exploding depth charges. Then between the last two attacks, a heavy underwater ripple explosion is heard.****
17 May 1944:
125 miles NE of Green Island. After midnight, the FRANKS drops a pattern of 13 depth charges and sinks the submarine - probably the I-176 - at 04-01S, 156-27E, 150 miles N of Cape Alexander, Solomons. A diesel oil slick covers seven miles of ocean and various debris, including wood, cork and a geta sandal are sighted.
11 June 1944:
Presumed lost with all 103 hands NW of Buka.
10 July 1944:
Removed from the Navy List."

tom