• Pick up Handgun
• Turn on lights
• Kill the Yamirei in the engine room
• Kill Tomoe
• Kill Staircase Yamibito
• Kill Yamibito in 1st floor room
• Run back down Yamibito staircase

You will need to get the bracelet on the 2nd floor separately.

You can skip killing Tomoe however it's random if she gets killed by the lights downstairs. Here's a video for reference: