Kitamura, Motoyasu

Motoyasu Kitamura is the Spear Hero, one of the Four Holy Heroes summoned in Melromarc. Additionally, he is the main protagonist of the spin-off series, The Reprise of the Spear Hero.

Motoyasu is likely the friendliest of the four Legendary Heroes. It's mentioned that he is loyal to his allies. However, he is incredibly naive and gullible. He is generally a nice person; however, he's easily fooled by women. He will believe anything a woman says without any shred of evidence. When Malty framed Naofumi for rape, even though she had stolen his money and clothes both of which she gave to Motoyasu, he thoroughly believed her claims and became openly hostile towards Naofumi in her defense.

In the end, Motoyasu finally realized how much of a fool he was to believe in Malty and fell into depression, not knowing that these events had caused his Legendary Spear to unlock the Curse Series.

Motoyasu had lost all motivation. Naofumi tried to cheer him up by bringing him to a bar, but Motoyasu had neither the will or the strength to resist and let him do as he pleased. Because Naofumi had no idea how to cheer him up, Filo took on the challenge of trying to cheer him up, after multiple attempts, Motoyasu finally broke out in tears and held his face to Filo's chest sobbing. Thus began his deranged love obsession for Filo.

His personality did a complete 180 after he unlocked his curse series, developing an obsessive crush for Filo and starting to regard Naofumi with utmost respect as his father in law. At the same time, he changes from a skirt chaser to a Filolial lover, being unable to see women other than that of pigs and found disgusting their "reek" and enjoying spending his time surrounded by filolials. Additionally, he develops a fearless and bloodthirsty style of battle, without feeling concerned about killing or being covered in blood.

Motoyasu took Naofumi's advice and used the Power Up Method Naofumi mentioned to him, as a result, he ended up becoming the strongest Legendary Hero out of the 4 heroes. (at the end of volume 11)

(Source: The Rising of the Shield Hero Wiki)