This is story related and cannot be missed. It is unlocked towards the end of Chapter 01: Prologue. The Prologue consists of two main parts. The first part is much longer than the second part and consists of a combat sequence. The second part is non-combat and consists of the first main story mission, Reboot. Concluding the first part of the Prologue unlocks the achievement just before the second part begins.
You cannot save until you defeat the main boss of the first part of the prologue. It is an action-filled sequence that some might find challenging especially if they have selected one of the harder difficulties. A summary guide is provide in the spoiler section. I added this section in response of a comment
JernauGurgeh SF. made in the review of a game. He pointed out some players might find being thrown right into the action a little disconcerting and advises "to (1) use dodge constantly as it makes you invulnerable; and (2) keep your finger on RB at all times to fire a stream of bullets at everything and anything:"
*** Spoiler - click to reveal ***At the start of the prologue, the playable character, 2B, is in a combat aircraft in formation with other aircraft. Enemy fire destroys much of the formation before the player gains control. Then, the game begins its tutorial teaching how to fire, evade, and how to execute a heavy attack. The dodge or evasive maneuver is very effective, giving the character a split second of invincibility against attacks. Be particular mindful of a reddish beam. When you see it start to form, move away from it horizontally across the screen.
After destroying the initial enemies and hazardous orbs, the aircraft reconfigures into a flying mech. Continue to destroy the enemy using the same button commands as before.
Eventually, only 2B remains and the mech changes back into the aircraft configuration. There is a tunnel sequence that requires quick reactions to dodge obstacles and to select the open tunnels. At times, you have to fight enemies in the tunnels.
At the end of this area, the game crashes your aircraft and gives you control over the 2B character. The tutorial teaches the player how to maneuver and fight with the character. She is armed with heavy and light swords and a pod unit that shoots. The combination of dodging and using the pod's ranged attacks can destroy enemies while exposing 2B to minimal risk. Use these techniques as the tutorial has you fight through different kinds of enemies until you reach the mid-boss, Buzzsaw.
Observe Buzzsaws patterns, evading and shooting when its blades are moving. When the blades stop, move in with sword attacks. Defeating Buzzsaw triggers a cut scene and advances the Prologue.
The tutorial guides you through an abandoned factory until you reach the boss fight, a gigantic weapon system called Goliath. It starts with twin buzzsaws each similar to the earlier mid-boss, before engaging Goliath proper. This is a multi-phased battle where evasion and attack are equally important. Your companion, 9S, joins the fight but encounters difficulties and you are given the task of rescuing him.
Eventually, the battle ends and triggers a cut scene. Following the cut scene, you will find yourself in the bunker and the achievement will unlock.