There are two sequels to this series:
Zoku Kindan no Koi wo Shiyou and
Kindan no Koi de Ikou.
Seigi finds himself in over his head when a powerful girl, using the same secret weapon, violently pursues him in order to retrieve it. His skill at martial arts may not be enough to keep him alive, but will he be able to learn how to trigger the power of his tattoo in time?