I found the certificate... and a "Official" U.S. Marine Corps Photo.
The photo shows 12 soldiers on the front and ont he back says:
"As the USS GRIMES, a troop transport steamed into Tokyo bay bearing the first American landing party of Marines, eleven Iowan's were aboard heard singing a song written by another Iowa... Meredith Wilson.. "Ko-Toky-I-O."Pictured here are a group of Marines who made the first landings and Navy men who handled and directed the landing boats.
Left to right, top row, are:Marine Private First Class Nelts (sg) T. NElsoen, 2426 Council Bluffs, Iowa, Navy Lt (jg)Clifford W. Parker, 1233 19th St., Des Moines, Iowa, Navy Lt. (jg) Carrol F. Johnson, 648 13 Ave., North Clinton, Iowa; Ensign Claude de St. paer, Storm Lake, Iowa; Marine Private First Class Marvin H. Harms, Buffalo Center, Iowa;Marine PRivate Jerome A. Coppious, 23 East Broadway, Colfax, Iowa;Bottom Row, left to right:Marine Private First Class Robert E. Gray 1415 44th St., Des Moines, Iowa;Seaman Second Class Gene Query, 21 Seventh St., Southwest, Mason City, Iowa;Marine Private First Class Paul Sacce (spelling??) Centerville, Iowa;Marine PRivate First Class Charles Sanders 1330 Norton, Des Moines, Iowa;and Marine Corporal William H. Mullan (my father) Manchester, Iowa
The Tokyo Landing Certificate:
I've tried copied the words (capitalizing as in the certificate and the photo).
TASK FORCE THIRTY-ONE Be it known to all to whom these presents may come that Cpl William H. Mullan as a member of TOKYO BAY OCCUPATION FORCE (TF-31) participated in the initial landing and occupation of the TOKYO BAY AREA and THE CAPTURE OF HIJMS NAGATO which act symbolized the unconditional and complete surrender of the Japanese Navy. 30 AUGUST, 1945 Signed by 3 signatures I cann't make out but titles were:
Brigadier General United States Marine Corps Commander Fleet Landing Force (signature looks like last name of "Clement" but hard to tell)
Commanding Officer (signature looks like last name of Osipoff)
Rear Admiral United States Navy Commander Tokyo Bay Occupation Force. (looks like Ose??ve Ra?g???)