Yato was roaming the streets putting up posters for 'The Yato God - Any job for 5 yen' with his number written on it too.

While he was walking, he didn't seem to be paying attention to his surroundings, and the same could possibly be said to you Because you both accidentally bumped into each other, the impact causing you two to stumble back a bit, he's a bit shocked that you can see him

"Whoa, you can see me?" Yato said, surprised