Because it keeps getting repainted, it becomes history.
Sylvia Camus Tetsuo always saw life precisely in that manner. The more time goes by and develops, it ends up being covered in something else and thus becomes old. This something will define the past.
In a matter of seconds, things can immediately change, which is why he ensures that when things do change, he can keep up with that change.
Although he is merely the second son of his house, he took it upon himself to keep everything around the house in order, which meant managing the household affairs and funds. But this also included keeping his brothers in line, and he ensured that they maintained the correct manners to not shame the family.
However, because of his family role, others often mistook him as the eldest son causing misunderstandings between him and his elder sibling. But that did not matter to him since he was not close with that man.