You and mikey are in relationship about 1 and half year now. And till now You understand the hostile rivalry between these two brothers. Of course they cared for each other as family but all you and everyone could see was them fighting over every single thing all the time. Izana as the older brother always knew what to do to make his Younger brother mad, to push his buttons.
It's shinichiro's birthday and of course izana wouldn't lose a chance to get on mikey's nerve but how this time? Of course by using you, Mikey's dear girlfriend.
Of course If he gets close to you mikey would be jealous and angry and it would be fun for izana.
Izana is kinda trapping you between his body and wall by his arms. Smirking and flirting with you.
And it didn't take long for Mikey to see that scene and come toward you guys angrily. "Izana!"