"Mutual Love" is the sixteenth episode of the Durarara!! anime and the seventeenth episode overall.
In a direct continuation of the previous episode, Niekawa is waving his knife wildly and proclaiming his love for Shizuo. Shizuo rips the door from Kyouhei's van and uses it as a shield as he crashes into Niekawa, knocking him out cold. Celty took his knife and took Anri home, leaving Niekawa with Kyouhei's gang. Celty relates these events to Shinra when she gets home.
At home, Anri appears to be in shock from the evening's events. Her doorbell rings, and she answers it, finding Haruna Niekawa at her door.
In their apartment, Celty shows Shinra the knife that Niekawa had used to attack Anri. Shinra tells Celty about the demon blade Saika's desire to love humanity. In Anri's apartment, Haruna tells Anri about her love for Takashi Nasujima. Shinra explains to Celty that Saika uses its human host to slash its victims and spread its feelings of love through people. Haruna tells Anri that while her love for Nasujima allows her to forgive him if he shows feelings to someone else, she'd never be able forgive the other woman. She explains that she had sent others, including her father, to attack Anri, and each attempt had failed. Her eyes begin to glow red as she reveals she has come to do the job herself.
Shinra notices the "Made in Japan 2009" engraving on the knife Celty took from Niekawa. He and Celty come to the conclusion that the knife isn't Saika and that Saika is still at large.
Celty and Shinra realize that Saika has been spreading. Over the city, slashing victims with glowing red eyes are shown slashing others.
Shizuo stands outside Izaya's apartment in Shinjuku. As he goes to kick down the door, Izaya appears behind him. Shizuo demands to know how involved Izaya is in the Slasher incidents.
Izaya walks outside, preparing for a fight. Shizuo pulls a guardrail out of the ground, but Celty shows up, stopping their fight. She shows Shizuo the recent chat room messages from Saika, and he immediately rides off with her.
Haruna opens Anri's door to find Nasujima. He is shocked to see her and runs away. She follows, promising to have "everyone else" kill Anri instead. A group of people with glowing red eyes and carrying knives begin to file inside Anri's apartment while she backs into a corner.
Shizuo and Celty arrive in South Ikebukuro Park. Countless numbers of people with glowing red eyes and carrying blades - ranging from axes to butterfly knives to scissors - move toward them. Anri's three bullies stand ahead of the others. They explain their desire for Shizuo's strength, promising that they love him. He laughs, and though Celty is alarmed, Shizuo is glad for the chance to use his strength to its extent. He tells Saika's Army that he hates them as he runs toward them, prepared for a fight.
Setton views the chat room and sees that Saika has been posting disjointed sentences and phrases, saying 'The timing was bad.' They repeat Shizuo Heiwajima's name again and offer to wait for him at South Ikebukuro park.
- Shuuji Niekawa
- Shizuo Heiwajima
- Saburo Togusa
- Erika Karisawa
- Walker Yumasaki
- Kyouhei Kadota
- Anri Sonohara
- Celty Sturluson
- Shinra Kishitani
- Haruna Niekawa
- Izaya Orihara
- Takashi Nasujima
Shizuo: "I'm off to Shinjuku to kill Izaya. I'll be back."
Erika: "Oh man, Shizu-chan totally has the hots for Izaya! Boy-on-boy love is so much fun; I love it!"
Shizuo (to Izaya): "99% of the time, whenever random violent crap happens, it seems you're somehow involved."
Izaya (about Shizuo): "Unbelievable. One moment he's dumb as an ox, the next he's sharp as a whip. And it's because of this very reason that I hate him so much."
Anri: "You can't judge other people by how they live and just decide if they're weak or strong."