September 20th, 2012. Location: Shibuya, Shinsen district, Kurenai conference hall. 10:00 AM.

Three years have passed since the horrors of the New Generation Madness and the Noah II incident. Shibuya has slowly recovered from the massive earthquake caused by the Third Melt that claimed countless lives. You hear footsteps approaching as Nishijou Nanami climbs the stairs, humming cheerfully with uncharacteristic enthusiasm.

Your relationship with your younger sister has improved dramatically since those dark days. Both of you suffered deeply, but now life has returned to some semblance of normalcy. You're both healing, taking things one day at a time.

Nanami appears at the top of the stairs carrying a small basket of fruit, clearly intent on making sure you eat something healthy for a change. She approaches the converted container that serves as your home - an unlikely living space equipped with a washing machine, kitchenette, and laundry drier tucked away on the top floor of the conference hall.

She's been here countless times before as part of her "survival check" routine. She'd barge in, criticize your lifestyle, bicker with you briefly, then leave complaining about how mean you are - yet she always comes back, unable to hide how much she truly cares.

Nanami stops in front of your door and knocks once.

Silence. No response.

Not unusual. She'd actually be concerned if you answered immediately. You've never been one to greet her promptly, usually avoiding these visits like the plague. She knocks again, a little louder this time.

Still no response.

Nanami refuses to be deterred. She continues knocking while calling out to you.

"Big bro...!"

The door remains closed.

Now genuine worry mixes with her annoyance. What if something happened to you? She pounds harder on the door, increasing the volume until you finally open it. Her serious expression instantly transforms into her signature mischievous smile.

"Routine survival check!"

She steps inside without waiting for an invitation.

"At least say something when I knock! I thought you might be dead or something! You weren't answering your phone either! Were you ignoring my calls again? You're seriously the worst...!"

Nanami places her hands on her hips, glaring at you with exaggerated irritation that doesn't quite mask her relief. Her eyes scan your living space critically.

"Wow, this place is still a total pigsty... Can't you tidy up even a little bit occasionally? Don't tell me you're waiting for a girlfriend to do it for you? Well whatever - I guess I'll just have to clean it myself."

Despite her harsh words, an endearing smile tugs at the corner of her mouth, betraying her true feelings about this ritual of yours.