In 1987, a woman has complications while giving birth. The woman’s husband prays to his native deity that if she delivers his baby successfully, he would name the baby with the name of the deity. The baby is born without any problems and as per the wish, they name the baby, Kunjithapadham (Sivakarthikeyan).
As a boy, Kunjithapadham faces many problems and embarrassments due to his name,as his peer mates call him kunju or kunji. He decides to change his name. But his mother falls ill and he prays to god that he would never again wish to change his name.
Years later, Kunjithapadham’s mother dies. His friend Peter (Sathish) advises him to change his name in order to have a change in his life. After meeting an astrologer (Manobala), he renames himself “Harish”. Luck starts to him from that day onwards. He falls in love with Geetha (Priya Anand) and succeeds in winning her love. He later gets a job and life goes smoothly for him. One day, his lottery ticket hits victory and he must cash it in for a television as a prize. But, the lottery has registered his name as ‘Kunjithapadham’. He makes up the drama with Peter and gets the television, but later faces problems and Geetha finds out his true name. Geetha berates Harish for lying to her about his name and that he needs to succeed something in life in order to win her heart.
Harish decides to participate in the Chennai Marathon to achieve something in life. He meets with a trainer (Jayaprakash), who takes him to his former student Valli (Nandita) who had quit athletics. She agrees to train Harish and later, Harish sees her crying in the terrace with a photo of her dead father. Harish asks her to tell her past.
Valli was a naturally talented athlete from her young days. Her father (Sharath Lohitashwa) supported her talent and spoke with many men to get her past many tournaments. She got into State level tournament where she beat the rookie of the corrupt coach Raja Singh (Ravi Prakash). Infuriated, Raja Singh accused Valli of failing a gender verification test. The board punished Valli and stopped her from participating. Heartbroken, Valli’s father died of a heart attack.
Hearing this flashback, Harish is moved and decides to win the marathon. Geetha also urges him to win it for the sake of Valli. During the marathon, Harish faces stiff competition from another one of Raja Singh’s rookies but eventually wins the race and publicly reveals Valli’s innocence . Raja Singh is arrested, and Valli resumes athletics.
Harish later opens and runs a training academy under his original name. A man named Dinakaran (Attakathi Dinesh), acting on Harish’s advice, proposes his love to Valli, and she accepts.