The film stars Prashanth, Simran and Laila, while Raghuvaran, Jai Ganesh, Vinu Chakravarthy, Vaiyapuri, Charle, Dhamu, Lawrence Raghavendra, Fathima Babu and Jyothi play supporting roles.

They spend almost all their time together, and she seeks him out as a refuge due to her stepbrother Panneerselvam, whom she dislikes but is forced to live together with.

One day, while dropping off Bhanu at a bus stop, Shankar sees a pretty girl Sarika and likes her.

However, both Shankar and Sarika are unaware that they themselves are the prospective suitors arranged for each other by the parents and thus avoid the formal meeting ceremony.

Chidhambaram gets irritated and creates a ruckus at Sarika's house and after a huge argument, both the parents cancel the marriage arrangements.

However, after so many confusions including a failed marriage arrangement with Sarika, Bhanu feels that she is rightfully destined to be with Shankar.

Meanwhile, Sarika learns about Bhanu from the bus driver Vellaisamy and realizes Shankar is innocent and reconciles with him.

Sarika is brought to the same hospital where Bhanu studies, and because of the ongoing doctors' strike, she is unable get any treatment.

Saran created the plot of Parthen Rasithen combining two elements: his experiences of travelling in bus to college and incidents that happened in the life of his brother K. V. Guhan which inspired him to make a script on it.

[7] Venky of Chennai Online wrote "A very good effort by Saran and Bharadwaj after their successful Amarkkalam".

Prashanth's plausible reactions to Simran's unrelenting moves, saying that he cannot think of her as a venomous person, are natural, and his performance is laudable.

[12] Malini of Chennai Online wrote, "The film begins promisingly enough and moves at an interesting pace in the first half.

[15] In 2016, Vijay Sethupathi was asked about his favourite romantic moments in cinema and what Valentine's Day means to him.

[16] Simran's performance was featured in JFW magazine's list of "5 Heroines Who Stunned Us By Playing Negative Roles".