Okay kiddo, "ono otsū" is actually two separate words in Japanese: "ono" and "otsū". They are written in special characters called kanji.
"Otsū" is a city in Japan, kind of like how we have different towns and cities where we live. It's a nice place to visit, with mountains and beautiful temples, and lots of delicious food to try.
Now, "ono" can mean a few different things depending on how it's used, but in the context of "ono otsū", it's actually a surname. In Japan and some other countries, people's names are written with the family name first and then the first name. So "ono" is like a last name for someone named Ono who lives in the city of Otsū.
So when you hear "ono otsū", it's like saying "Mr./Ms. Ono from Otsū". Just like you might say "Sally Smith from New York". It's a way of identifying someone by where they're from and what their last name is.
Pretty cool, huh? Japanese names and places can be a bit different from what we're used to, but that's what makes learning about different cultures so interesting!