© 2006-2009 Bob Hackett, Sander Kingsepp and Peter Cundall
7 September 1944:
Tamano. Laid down at Mitsui Engineering &
30 December 1944:
Launched and named OJIKA. 
21 February 1945:
Completed and registered in the Sasebo Naval
District. Attached to the Kure Guard Unit for workup and training.
28 March 1945:
S of Kyushu, Japan. A Japanese aircraft detects and
bombs a submarine. OJIKA and other warships are guided to the spot and deliver
an intensive depth charging that is heard by SILVERSIDES (SS-236), SEA DOG
(SS-401), HACKELBACK (SS-295) and THREADFIN (SS-410) operating in adjacent
waters. After two hours, a large oil slick appears. 
5 April 1945:
Reassigned to the General Escort Command's First Escort
26 April 1945:
Reassigned to the First Escort Fleet's 103rd Escort Squadron.
28 April 1945:
At 0600, OJIKA departs Moji for Shanghai with kaibokan
INAGI and CD-59 escorting convoy MOSHI-05 consisting of MIHO MARU. At 2000, that
same day, the convoy arrives at Chinkai, South Korea.
29 April 1945:
At 0500, departs Chinkai.
30 April 1945:
At 1408, LtCdr Allen R. Faust’s USS TREPANG (SS-412)
torpedoes and sinks MIHO MARU. The kaibokan counter-attack and drop 27 depth
charges, but TREPANG escapes undamaged. The escorts head towards Shanghai.
1 May 1945:
At 1300, OJIKA reports her position as 33-20N, 122-15E, course 040, speed 14 knots.
2 May 1945:
Yellow Sea. That night, LtCdr Russell Kefauver’s USS SPRINGER (SS-414)
attacks a ship and two escorts. Kefauver fires a spread of four torpedoes. SPRINGER's crew hears the first explode and then see and hears two more hits which sink OJIKA with all 226 crewmen.
3 May 1945:
At 1014, USN codebreakers intercept and decrypt a message that reads: “Summary of disaster to OJIKA: OJIKA and CD-59 were on station abeam this ship distant 1.5 kilometers proceeding on course 240 degrees. ----about 5 minutes after CD-59 had picked up something resembling an enemy submarine and was observing it, OJIKA was seen to open fire. A few seconds later there was an explosion and a pillar of fire --- and sank. At 0930, oil and debris were seen to the northeast of the disaster ---.”
At 1212, codebreakers decrypt a message from minesweeper W-20 that reads: “Am heading to the scene of the OJIKA disaster ---.”
Yellow Sea. 140 miles SE of Mokpo, Korea. CD-25 is proceeding to the scene of the sinking of OJIKA. At about 2300, Kefauver’s SPRINGER makes a night surface radar attack on CD-25. Kefauver fires six torpedoes and claims three hits on the small escort. CD-25 capsizes and sinks at 33-56N, 122-49E.
5 May 1945:
Yellow Sea. 140 miles SE of Mokpo, Korea. W-20 is proceeding to the scene of the sinking of OJIKA, but W-20 is intercepted enroute by LtCdr Allen R. Faust's USS TREPANG (SS-412) that torpedoes and sinks her at 33-56N, 122-49E.
7 May 1945:
At 1915, codebreakers decrypt a message sent earlier by W-20 regarding the event of 3 May that reads:“In accordance with Yellow Sea Area Force OpOrd No. 39, CD-25 and W-20 left the vicinity of Shichihatsu Shima the morning of the 3rd to proceed to the scene of the torpedoing of OJIKA .”
8 May 1945:
At 0515, codebreakers decrypt a message from the CO of the 103 Division: “Hoisted flag in OKI and sortied from Niioshima to carry out search for CD-25 and W-20 and to sweep for enemy submarine.”
The Yellow Sea Area Escort Force presumes CD-25 and W-20 were lost with all hands. 
25 May 1945:
Removed from the Navy List.
 OJIKA was also known as OGA. The first Japanese character O can be read as Otoko, Dan or Nan and the suffix Roku can be read also as Shika (Jika) or more commonly Ka or Ga. So either is possible.
 If, in fact, a submarine was lost to these attacks it may have been Cdr David R. Connole's veteran USS TRIGGER (SS-237). Alternatively, TRIGGER may have fallen victim to a mine. There has been no official determination on the cause, or even the location, of her loss.
 On 3 May '45, USS SPRINGER torpedoes and sinks CD-25 at 33-56N, 122-49E.
 On 5 May '45, USS TREPANG (SS-412) torpedoes and sinks W-20 at 33-56N, 122-49E.
Thanks go to John Whitman of the USA for info on CNO intercepts of Japanese messages.
-Bob Hackett, Sander Kingsepp and Peter Cundall