Kimura from Guard
Unless his hands are already on the mats - which would mean he made a mistake - slide your hands under his after he walks them back to your hips.
Pop your hips up while bringing both your arms - and his - up and outward in a big sweeping motion.
Open your guard by uncrossing your feet, but keep your knees tight to his hips.
Let go of one wrist so you can reach your arm over his opposite shoulder.
Grab your own wrist.
Option 1: Rotate your body so that your shin is aligned with his spine and his hip is trapped with your other leg. Keep his upper arm against your chest while lifting his wrist upward and toward his body.
Option 2: Trap his leg with your leg while keeping your other leg tight to his hip. Stay - mostly - flat on your back. Keep his upper arm against your chest while lifting his wrist upward and toward his body.