TOMONE (just like the others)
3 months. It more long than the time that Yato had ever spent with his other regalia. But less long than the time that he spent with his two first regalia: Hiiro (probably his whole lifetime) and Sakura (about a year).
The time Yato spent with Tomone not really different with the time he spent with the other regalia before her. Like them, she also complaining about almost everything. His cloths, his job(less), his home(less), his (impossible) dreams, his laziness, his (of course) 'sweaty' hands, his personality, his money(less), and any other things that really unnecessary and unimportant for him. Human things. And their relation also had to ended because of the same reasons just like the regalias before her.
Just like them, she threw him away and left. Looked for another better place than his. Tomone has no differences with any other regalias Yato ever had. They, who easily picked a better master than him. But Tomone was his only former partner who still wanted to come and saved him from death after their ties were cutted off.