In "Mikan no Hana", Hirosue plays a housewife who hates her elder sister for leaving behind her and their mother behind in their hometown so that she could become a novelist in Tokyo. One day, she comes to know a shocking truth from her elder sister. Hirosue commented that the climax scene when the sisters come face to face was especially memorable for her.
In "Umi no Hoshi", Ito plays a company employee who was raised single-handedly by his mother. When he grows up, he starts to find out the truth behind the disappearance of his father during his childhood.
As for Hamada, he plays the lead character who is a popular singer in "Kumo no Ito". However, he tries to conceal the fact that he came from an island especially since he had a hard time during his childhood due to a crime his mother committed. He returns to his hometown for the first time in 7 years but accidentally falls into the sea and goes into a coma.
Sources: Sanspo / Yomiuri Hochi