Masatsugu is the head of the wealthy Kashiwara family. He lost his entire family when he was young. Masatsugu contributes money to help schools and give speeches to students. Masatsugu's life story is well known among his neighbors. He is also shown to be very stubborn and holds to his views with no compromise.
Sarina is Masatsugu's granddaughter. Kirari is Sarina's best friend and often visits them. Masatsugu enjoys karaoke with them.
Masatsugu lost his entire family due to blowfish poisoning. He was the only one who did not eat the blowfish. He later lived with his relatives. Masatsugu was drafted for World War 2. He returned safely and started the Kashiwara group with help from friends he met in the military. He married some time after his business took off. He wife passed away soon after giving birth to 2 sons.
His first son Kenichi married Yasue who had a weak constitution. Masatsugu did not approve of their relationship and argued that they were too young and she was ill. They could not reach an agreement and Masatsugu disowned Kenichi. A few months later, Kenichi's wife Yasue passed away and Kenichi committed suicide shortly after. Yuji rescued Sarina and gave her to Masatsugu's care. He loved her dearly and is over-protective of her.
Chapter 2: Road to Ruin?
Right after the Second Literature Club band's performance at the school festival, Masatsugu grabbed Sarina, stormed off, and grounded her. Sarina then ran away to join the band tour.
On Sarina's path, she suffered from high fever soon after she returned. Masatsugu brought her back to his home town of Nagano and grounded her again. Yuji argued that Masatsugu is keeping an iron grip on Sarina. Masatsugu argued that he will allow her freedom once her health improved.
A few days later, Masatsugu held a meeting with Shikanosuke and Sarina. He demanded a good future for Sarina if he will allow their relationship. Shikanosuke was unable to make concrete promises and Sarina explained that she would still love him regardless. Masatsugu was enraged and blamed Sarina for being as stubborn as her father.
Shikanosuke then mentioned that Masatsugu still loved his son Kenichi and presented Kenichi's will. Masatsugu then broke down because he had always suspected that Kenichi still loved him but Masatsugu was in denial. He then approved of Shikanosuke's relationship with Sarina.
Shikanosuke went fishing with him the next day and Masatsugu explained that he is always welcome to the Kashiwara household.