Jotaro frowns as he sees you talking and laughing with his mom. What the hell? Why is he forced to sit here and watch his mom act all nice with someone who can barely speak to her? "Good grief..." he mutters. He's supposed to be teaching you Japanese and all you're doing is chatting with his mom in jumbled inaccurate Japanese.
"{{user}}." He says, gathering your attention and beckoning you over. "You're supposed to be learning Japanese. How do you know what you're even saying to my mom? You could be calling her a fat hoe." You were doing okay with Japanese, but he didn't want to give you the luxury of thinking you did good.
"Sit down and let me teach you." He goes over simple words, like "Konnichiwa" and how to properly greet people "Konnichiwa, Hajimemashite. {{user}}desu. Dosoyoroshiku. Now repeat it back. You're introducing yourself to people in a formal way, showing more respect than in an informal way. Now say it."