Mandharam begins with the all too familiar trope - the schoolboy who spends his days dreaming about his childhood sweetheart and classmate, who, at the end of school, lets him know that she has a 'muracherukkan'.
| Actor | Role |
|---|---|
 Asif AliRajesh | Rajesh |
 Varsha BollammaCharu | Charu |
 Megha MathewRemya | Remya |
 Jacob GregoryTittu | Tittu |
 IndransJacob | Jacob |
 K. B. Ganesh KumarRajesh's Father | Rajesh's Father |
 Anarkali MarikarDevika | Devika |
 Arjun AshokanRenjith | Renjith |
 Vineeth VishwamNazer | Nazer |
 Arjun NandhakumarRoshen | Roshen |
 KausalyaRajesh's Mother | Rajesh's Mother |
 Srikant MuraliVenu | Venu |
 Unni Rajan P DevRajesh's friend | Rajesh's friend |
| KKarthika KannanNot listed | Not listed |
 Krittika PradeepJanaki | Janaki |
 Raveena RaviDevika (Voice) | Devika (Voice) |
 Nazeer SankranthiNot listed | Not listed |
 Kannan SagarSecurity guard | Security guard |
 Sreeja DasParvathy | Parvathy |
 Krishna PrasadNot listed | Not listed |
| SSandeep NarayanPolice officer | Police officer |
 Eric ZachariahYoung Rajesh | Young Rajesh |