BK 的新女演员露西娅将面临一生中最困难、最[X_X]的数学测试。

露西娅（Lucia）曾经是一名恶霸，小时候曾欺负过莱克斯（Lex），一段时间后她得到了报复，她将她关在一个房间里，戴上手铐在墙上。 她让他穿上他们小时候上高中时穿的校服。 Lex进入Lea所在的房间，带着一个装满绳子的盒子到达，解开Lucia的手铐，并用绳子绑住她的双手，将Lucia绑在竹子上，将她的身体伸到地板上，双手向前，用竹子堵住她的嘴 堵嘴，这让她能够在考试中说出足够的口语。 他绑住每条腿，将脚踝与大腿连接起来，最后将每条腿固定在墙上，拉紧绳子，使腿无法闭合并保持打开状态。

一旦他按照自己的意愿把她绑起来，他就拿出了超级强大的日立，他开始了数学考试，露西亚在高中时数学很差，莱克斯很优秀，露西亚嫉妒她并取笑她。 现在露西亚在莱克斯的控制之下。

Lex告诉她规则，他会问她不同的问题，如果她想获得自由，她必须把一切都做好，否则她将受到惩罚并被拘留。 她回答每个问题的时间越长，他给她的[X_X]里的日立的力量就越大，随着时间的流逝，如果没有正确的答案，力量就会逐渐增强，直到她答对或放弃。

这里我们看到一个很长的场景，莱克斯给她考试，不同难度的数学运算，露西亚的所有[X_X]，在她同意的情况下都是真实的。

露西娅没有通过测试，莱克斯用臂缚器挡住她的手腕和手臂，将她绑在竹子上来惩罚她。 露西亚失败了，很快她就会有另一次机会，另一次考试……Introducing Lucia, BK's new actress, she will face the most difficult and orgasmic math test of her life.

Lucia is a former bully who used to bully Lex when she was young, after some time she has gotten her revenge, she has her held in a room, handcuffed to the wall. She has made him dress in the school uniform they wore to high school when they were young. Lex enters the room where Lea is, arrives with a box full of ropes, unties Lucia's handcuffs, and ties her hands with ropes, ties Lucia on the bamboo, with her body stretched to the floor and her hands forward, gags her with a bamboo gag, which allows her to speak enough for the exam. He binds each leg, joining ankles to thigh and finally anchoring each leg to the wall, tightening the ropes so that the legs cannot close and keeping them open.

Once he has her tied as he wants, he takes out the mega powerful hitachi, he starts the math test, Lucia was very bad in high school with math, Lex was excellent, Lucia was envious of her and made fun of her. Now Lucia is under Lex's control.

Lex tells her the rules, he will ask her different questions, she has to get everything right if she wants to be free or else she will be punished and kept in detention. The longer she takes to answer each question, the more power he will give her with the hitachi in her pussy, it will progressively go up as the seconds pass without the correct answer until she gets it right or gives up.

Here we see a long scene where Lex gives her the exam, with different mathematical operations at different levels of difficulty, all the orgasms that Lucia has, are real with her consent.

Lucia fails the test, Lex punishes her by putting an armbinder blocking her wrists and arms, tying her to the bamboo. Lucia has failed, soon she will have another chance, another exam...