Kankin Shinsatsushitsu - Kyousei Kozukuri Tanetsuke Chiryou

Comic adaptation of the audio voice drama "Confined in the Exam Room Forced Pregnancy Treatment".

Joutarou is a doctor who's returned home to take care of the family clinic after his father fell ill.
You coincidentally happen to meet him as a patient and he greets you with joy.
He has always had feelings for you, his high school classmate, but you never paid him much mind.
To push him away, you tell him you're only back in town temporarily, and already have a fiancé.
Nonetheless, he manages to force his way through your refusals, offering to drive you to the train station and see you off the next morning...

However, hidden in his bag, he brings with him a tranquilizer powerful enough to knock out even a horse...

(Source: DLsite garumani)