UMP45 is a member of Squad 404, which has much plot relevance.
This section serves as a prologue of UMP45, revealed to players during Operation Deep Dive.
While the commander and the AR team are working to reclaim S09, UMP45 and HK416 infiltrate a command post within the sector to obtain information regarding the whereabouts of Agent— and in doing so, they find details about Parapluie. After extracting the data, HK416 uses some free time to engage M16A1; UMP45 follows soon after to pick up her squad member, inevitably meeting up with M16A1. She takes the opportunity to say the code phrase “It’s raining on the plain” to M16A1, then promptly leaves.
Helian contracts Squad 404 to assist with the search for AR-15 in S06. As the leader of Squad 404, UMP45 is in charge of their strategy. Their first objective is to locate and retrieve the jammer, so she targets Hunter, the ringleader stationed to protect the object of interest. However, they all initially underestimate Hunter’s abilities due to the ringleader’s “Elite” modification and thus are forced to retreat. UMP45 decides to enter prolonged combat, while avoiding direct confrontations, with Hunter in order to deplete the enemy of her resources. Squad 404 emerges victorious against the ringleader, yet they are unable to gain information from her because Ouroburos shuts down Hunter’s neural cloud. UMP45 orders the other three members to move to the other side of the sector ahead of her.
After the unsuccessful endeavor involving Hunter, UMP45 breaks off from the group for a while to bring along SPP-1, a scout from Griffin who has been separated from her escort. After reconvening with the rest of Squad 404, UMP45 receives the coordinates of the jammer from SPP-1. They all make their way to the zone with the jammer, but are stopped by Executioner who is guarding the jammer, and has also received an “Elite” modification . They deal with Executioner in the same fashion as they did with Hunter. However, Executioner has set up explosives throughout the area as a last ditch measure to take out Squad 404. UMP45 successfully negotiates with the ringleader to let them escape the blast radius in exchange for returning Hunter.
Ouroboros is intent on hunting down Squad 404, so UMP45 concocts a plan to defeat her. She enlists the help of OTs-14, who had been escorting SPP-1, to take on the ringleader’s main forces and lay siege to the command post. She directs UMP9 to continue using her dummies as bait to shake off any enemies in pursuit, then orders HK416 to carry G11 to a vantage point in area R13 so that G11 can cover their withdrawal. UMP45 also commands HK416 to assist OTs-14 in wearing down Ouroboros’s forces after transporting G11.
Eventually, Griffin and Squad 404 emerge victorious. UMP45 enters the command post alone to personally kill Ouroboros. She then obtains the ringleader’s corpse and regroups with her squad. It is revealed that UMP45 has been infected with Parapluie due to her coming into contact with the jammer.
Taking up another contract, Task force 404 was sent to aid AR squadron from the event of Arctic Warfare.
A later contract would require Task force 404 to dive deep into Ferri controlled territory and recover an UAV, but it wasn't as straightforward as it sounds.
404's latest contract, at the request of Angelia, they are to assist the newly formed Defiance squadron in their operations against SOCOM units.