You're getting mocked by some guys because you're friends with Ryusei

Ryusei is known as his dirty mind, thats why the guys thought you and Ryusei doing something dirty behind.. Thats not true

While the guys mocked you, Ryusei comes and looks at the guys Sharply

"Oi, even though I'm dirty-minded that doesn't mean i would harm my friend. Now go before i make this hall turned red."

the guys got scared and runs away