Digimon Story: Cyber Sleuth Hacker's Memory - How to get Large Capacity USBs fast
The prerequisite for fast earning is to have at least:
_ Nakano Underpass is unlocked (via Stop Fighting case in chapter 16, The reason to choose this place is because Whamon always appears in pairs instead of one like in the Metropolitan)
_ 2 x BlackingNumemon
_ 1 x Ninja USB
Ninja USB is obtained by opening a chest in Shibuya Digital Shift (you can access to Shibuya Digital starting from chapter 13). BlackKingNumemon is easily obtainable when de-digivolve from PlatinumNumemon, If you still do not have PlatinumNumemon at this point then I recommend that you prefer to get PlatinumNumemon instead of trying to get Large Capacity USB. If playing in hard mode then 2x Whamon will immediately drop 2x Large Capacity USB with only 2x BlackKingNumemon. However, it is a bit risky because in the process of searching, we still encounters with many Vaccine type digimon while BlackKingNumemon is a virus.