This story happens about 4 years befora Rin and Yukio was founded by Shiro.
-Chapter 01.
Not long after Shiro finished his mission,he arrived in front of his house.He saw someone sitting,starring at the night sky up on the roof.
In curiosity,Shiro approached that person. ''Hey,what are you doing here?it's late already.'' He asked that person.
''im just sitting here and watching the moon,that's now shining bright in the night sky.i expect this is your house?i apologize,I'll go away from here immediately.''
''no problem,you can just sit here if you still wanted to.'' Shiro replied,then sat beside that person.
''what's your name?'' that