Otachi comes through the breach and begins heading for Hong Kong, it is however met and engaged by by several Jaegers just off the coast. At first the battle starts between Otachi and the two jaegers, Crimson Typhoon and Alpha Cherno, with Otachi having the upper hand over both of the giant mechs, before finally killing the crew of Crimson Typhoon using it's tail, and critically damaging Alpha Cherno using it's acid sac. Eventually another category 4 Kaiju, codenamed "Leatherback" , joins the fight and brutally kills the crew of Alpha Cherno. After both jaegers are down a third Jaeger, Striker Eureka, attempts to stop the two advancing kaiju and begins beating Otachi and on the verge of killing the creature with it's missiles but Striker is suddenly incapacitaed by Leatherback's organic EMP blast. Otachi then heads into Honk Kong where it's true mission is revealed, find and eliminate Dr. Newton Geizler, who had previously connected his mind to a Kaiju's and learned they are being ordered by other worldly beings known as the Precursors, to wipe out mankind so they can make Earth their home. Because Geizler's medeling into a Kaiju brain was detected by the Kaiju masters, Otachi was sent to silence him.
After wreaking havok on all of Hong Kong Otachi eventually finds it's target in an underground civilian bunker. Just as the Kaiju was about to devour Newton, Gipsy Danger intervenes just in time after having killed Leatherback, a brutal battle then ensues between the two giants. Gipsy uses a gint ship as a club by smashing Otachi several times in the face and body with it, before Gipsy is finally disarmed and violently thrown through several buildings by the creature. Just as Otachi attempts to use her acid sac on Gipsy the giant mech reaches down her throat and grabs hold of the acid sac in an attempt to rip it out, Otachi then uses it's deadly tail desperatly trying to kill the Jaeger pilots before Raleigh and co-pilot Mako Mori use the robot's coolant system to freeze and shatter the monster's tail, before finally ripping out it's acid sac. Enraged and in agony, Otachi leaps onto Gipsy Danger, wrapping her talons around it's chest. She then unfurls her massive wings and takes flight with Gipsy in tow. The Kaiju drags Gipsy through several buildings, and flies into orbit. Just as Gipsy's programs and function's are failing due to the atmosphere, Mako deploys gypsy's hidden weapon, a giant sword. The two pilots then use Gipsy's sword to slice Otachi's wing clean off, Gipsy is able to slow it's descent by firing it's nuclear reactor, Otachi however plummett's to it's death.
It is revealed later after a salvage team led by Geizler and black marketeer Hannibal Chau, begin to salvage what is left of Otachi's remains, that Otachi is in fact pregnant. The Kaiju newborn is able to kill several members of the salvage team and swallow Chau before strangling itself to death on its own umbilical cord. Newton and fellow scientist use the newborn Kaiju's brain to learn the secrets of successfully entering the Kaiju breach.
The baby's failure to kill Geizer presumably angered the Precursors, whom proceed to hasten and deploy an even stronger and more cunning Kaiju to finish what they started.