MTL'd from Japanese description:

The dead grandfather's memento was a device that stopped time!?
The main character, who has always been interested in Misaki, who doesn't get along with anyone in the class, uses a device that stops time to play a naughty prank.
She couldn't forget that feeling, and when she was looking for another chance and having fun with her intercrural sex, time began to move and her act was found out.
The latest issue of Tanaka Extract, which includes 5 episodes of the title work "Toki Tomeki" series and 9 works plus 1 newly drawn work.