Sumio Timeline

If there is one character in the whole GHM (Grasshopper manufacture) universe that could be considered the main protagonist of the main GHM titles it would be Sumio.
Killer 7 is the only "Kill the Past" themed game that Sumio did not take part in.
Mainly because Killer 7 takes place in an alternate reality specifically designed for Killer 7.
(In the world of the Silver Case, internet is used constantly. Some characters even check their e-mails daily. Whereas in Killer 7 all trans communication is basically outlawed.

Sumio made his debut in Suda 51's spin off of "Twilight Syndrome",known as the "Moonlight Syndrome".
During his younger years (18 yrs. old in Moonlight Syndrome) Sumio went by Sumio Touba. Sumio's surname during the Silver Case (25 yrs. old) was Kodai.
Finally in FSR he became known as Sumio Mondo.
Sumio also makes an appearance as a "Searcher" (Sumio's FSR look.) in the sequel called "Silver Case 25 ward".
(He again resumes his identity as Sumio Kodai.)

I am not exactly sure why he has a different surname in every game that he appears in,but it is made certain that each Sumio is in fact the same person... or identity at least.
(The ending of FSR has me wondering if every Sumio we see is just a shell with a ghost inside.)
Nevertheless Suda51 devised an official timeline for Sumio Mondo so I guess that's some proof that each Sumio that you play as is the same person in every game that he appears in.

NOTE: Sumio Mondo's birthday is 1113. Although in the original version of FSR, his birthdate was any number that you Jacked in when asked for your birth date.

-------- This is mainly just a log of official cases that the detectives of ward 24 previously worked on.

Sumio official chronology

Chronology Section establishment of 1990.11 Heinous crimes Department

1991.02 Kusabi (Tsuguro) and Ishikawa CASE: "Run off"

1992.11 Kusabi and Morikawa CASE: of "Royal nine". Kobayakawa and Ishikawa die in the line of duty

1994.04 Sumio 1st assignment CASE: "Power Girl"

1996.12 Kusabi and Morikawa CASE "Steel town" Together they try to dispose the place.

1997.10 Nakatagawa CASE: "Moon"

1998.07 Kusabi and Sumio CASE: "Gas Kids"

1999.01 "Pre-Lunatics"('Moonlight syndrome')

1999.01 "Lunatics"('Silver event') ~ PRELUDE

1999.03 "Decoy man"('Silver event') ~ CASE#1

1999.05 " Sumio and Hachizuka CASE: "After Camui"

1999.06 "Spectrum"('Silver event') ~ CASE#2

1999.07 "Parade"('Silver event')~ CASE#3
- Topdrunkee's note: It's around this time that Sumio Kills the Past. He is relieved of his duty after purposely failing the case#3 Parade. Parade ties in loose ends from the Moonlight Syndrome.

1999.08 "Kamuidrome"('Silver event') ~CASE#4

1999 " Sakura CASE: "Face"

1999.11 "Life cut"('Silver event') ~CASE#5

2000.01 Sakura CASE: Year 2000 compliance.

2000~ Kusabi, Kyouska, and Sakura CASE: "Lovers"

The exact time for the following cases are unspecified.

******* "Mulholland"('Flower, sun, and rain')

******* Kuusabi and Sumio CASE: "Hyena Shot"

******* "Life and money" Sumio and Koshimizu CASE: "Life and money"

******* Kusabi, Sakura, Sumio, Kyouska, and Koshimizu CASE: "Animal hunting"

******* Kusabi, Sumio, Kyouska, and Sakura CASE: Door lock"

******* Sumio CASE: "Angel X"