[Grandpa]

According to

A trace comparison with the remains of one the attackers was performed in all non-public areas, including the Tennou Royal Palace and the various royal families' castles. In all tests, the result was negative, showing that the unique composition of the attackers was not at these places.

This implies that every being has a 'unique composition'. What is this composition?

If the above is too vague-- How does one 'trace' this composition? Is it something a normal person is at all capbable of doing?

What 'remains' are necessary? Or rather, what exactly is required to 'trace' the 'composition' of something from them?

Are there methods of concealing one's 'compositon' or otherwise removing traces of it?