Episode 3 of Re: Zero introduces a character who is, quite literally, a white knight. Reinhard van Astrea is a member of the Royal Guard and is apparently so powerful and righteous that he’s known as the Sword Saint. He is also, incidentally, a minor character.
As anyone watching Re: Zero would be aware, the character with the white knight complex is actually Subaru, a hikikomori who is summoned from modern Japan, armed with only a cell phone and his wits. If Reinhard is supposed to represent the unattainable white knight ideal, then Subaru is the white knight whom the audience can relate to, a hapless young man who struggles through life (and multiple deaths) in the best way he can manage. So far in the story, he is motivated almost exclusively by his desire to save the girls he meets from death: initially the heroine Emilia, and later the twin maids Rem and Ram.
We’re not told much else about Subaru (to the detriment of the storytelling, frankly), but we’re expected to immediately understand and accept his obsessive desire to save these girls he barely knows. Why?