This was a small Japanese vessel usually not included in sinkings. Not credited to Robalo in JANAC. Note that Robalo was lost on this patrol, and information on the sinking of Kamo Maru was deduced using data gathered from multiple credible sources.

Many sources, including Cressman, credit this sinking to USS Lapon (SS-260), as did Alden-McDonald until their latest revision.

Current research notes from Alden-McDonald:

"Attack is not in SORG. ROBALO only sub missing in this area of South China Sea in mid-July 44. Senji Nipon Senmeiroku (Wartime Japanese Shipping Register) says XSCS Kamo Maru, Kurama Maru, & Kiku Maru left Manila 15 Jul for Kudat, Borneo. At 0045 on 18 Jul Kiku Maru reported being in gun action with sub at 08-44N, 116-41E, firing 6 rounds from 12cm mortar & dropping 2 depth charges. No mention of damage. Kamo Maru dropped out of sight same day and was presumed sunk by torpedo at 08-00N 114-38E, all 15 crew missing. {Warships of the Imperial Japanese Navy incorrectly attributes sinking to 260 LAPON.}"

Alden gives a detailed description of his conclusion that Robalo rather than Lapon sank Kamo Maru and Kuama Maru in an article he wrote for the October 2012 issue of The Submarine Review, titled "A Message from the Deep." (external link)