Follow the light until you pass the third streetlamp and before you reach the fourth streetlamp. Or just after you passed the first ball of light.

The three streetlamps behind you.

The fourth streetlamp in front of you.

Then just turn right and look between the buildings and you will see an alley with a known mech. Just walk past the fence and go inside. Do not worry about dark mirai shooting you she cant shoot into the alley. The dead can not follow you. The hands will not do anything either.

The alley in the distance.

Just walk up to the mech as closely as you can and you will get the achievement.

This is what the achievement looks like.

Be careful when leaving the alley though.

If this guide gets some attention I will probably make a guide about all the achievements from this game since it took some time for me to get them as well.
Thanks for reading and I hope this guide was able to help you.