Here is the total lifetime hardware and software sales chart for the Sega Katana! All worldwide physical sales included as of TTL 2018, no digital download sales included (even though the Katana did have a bigger digital download storefront than the Wave because of the iPod Play, we're not counting any digital sales until the seventh generation).
Katana Total Hardware Sales: 37,214,888
North America: 16,303,715
Japan: 10,958,314
Europe: 8,172,430
Other: 1,780,429
1. Sonic Neon: 13,870,652
2. Sonic Rover: 6,581,920
3. Virtua Fighter 4: 5,702,198
4. Virtua Fighter 5: 3,809,751
5. Tony Hawk's Pro Skater 2: 3,705,924
6. Endotherm: 3,277,589
7. Revolution Alpha: 2,908,334
8. Soul Calibur II: 2,805,296
9. Return To Three Mile Island: 2,780,561
10. Harry Potter And The Sorcerer's Stone: 2,649,281
11. No One Lives Forever: 2,560,773
12. Super Monkey Ball: 2,276,930
13. Stage 8: Three Mile Island: 2,203,854
14. Sega Superstars: 2,174,818
15. Tony Hawk's Pro Skater 3: 2,151,236
16. Commander Keen: Worlds United: 2,089,415
17. No One Lives Forever 2: A Spy In H.A.R.M.'s Way: 2,028,594
18. Guitar Hero II: 1,975,314
19. NiGHTS Into The Labyrinth...: 1,960,557
20. Shenmue III: 1,906,581
21. Commander Keen: A Stitch In Time: 1,835,554
22. Resident Evil 4: 1,827,385
23. Aerio 2: Hurricane Force: 1,788,653
24. Sonic: Ring Guardians: 1,769,316
25. No One Lives Forever 3: She Lives For Danger: 1,766,595
26. Tony Hawk City: 1,746,591
27. Wheelman 2: 1,718,654
28. White Mountain 2: 1,717,424
29. Skies Of Arcadia 2: 1,704,953
30. Extremis: Human Nightmare: 1,616,374
31. Vintage Speed Series Gold: 1,607,842
32. Battle Engine Aquila 2: 1,600,491
33. Thrillseekers: Spring Break: 1,585,097
34. Hitadake No Gane: 1,572,119
35. Tom Clancy's Delta Force: 1,570,299
36. Dead Midnight 3: 1,550,684
37. Sonic Revolution: 1,541,958
38. Aerio: Ride The Wind: 1,516,955
39. Knuckles And Bit: 1,492,843
40. Need For Speed Unleashed 3: 1,466,059
41. Blackheart 4: 1,418,951
42. NFL 2K1: 1,417,882
43. NiGHTS: Dream's End: 1,416,773
44. Turok Evolution: 1,415,939
45. Katamari Damacy: 1,415,372
46. Super Monkey Ball 2: 1,413,967
47. Tak And The Power Of Juju: 1,386,970
48. Madden NFL 06: 1,381,768
49. Shenmue II: 1,380,957
50. Turok: Extinction: 1,380,914
51. Dead Midnight 2: 1,307,492
52. Cardcaptor Sakura: School Life: 1,305,974
53. Aerio 3: Prisoner Of Captiva: 1,305,928
54. Arbiter Of Sin 3: 1,285,496
55. Phantasy Star Online: 1,279,356
56. The Casino Job: 1,262,484
57. Enter The Matrix: 1,228,491
58. Madden NFL 05: 1,209,756
59. Rome: Total War: 1,200,581
60. Narcotics Squad: Old Habits Die Hard: 1,185,763
61. NFL 2K2: 1,180,396
62. NASCAR 2K2: 1,180,294
63. Devil May Cry: 1,168,471
64. Vintage Football Challenge: 1,154,295
65. Elite Strike Raiders 2: 1,151,947
66. Jet Set Radio: 1,138,296
67. Naruto Ultimate Ninja Clash: 1,132,197
68. Street Fighter Omega: 1,104,974
69. Sega Derby 2003: 1,098,424
70. NBA 2K6: 1,095,471
71. Virtua Quest 4: 1,090,583
72. Tekken Tag Tournament: 1,080,394
73. Chu Chu Rocket: 1,065,928
74. Princess Revolution: 1,059,783
75. NFL 2K5: 1,034,197
76. Tick And Tock: Timebreak!: 1,030,295
77. Virtue And Vice: 1,019,486