Tear Jerker / Tenrou Sirius the Jaeger

• Dr. Hanada's death in Episode 2. It causes his daughter being scarred for life and also impacts Yuliy's worry over whether killing all of the Vampires was a good idea.
• Yuliy's past in Episode 3: Basically, his clan and his village got decimated by the Vampires including his mother's death, and one of the mementos that he kept from his mother was torn apart by the Vampires.
• The hurtful revelation that Willard helped the vampires to discover Yuliy's hometown and the latter ended up destroying it in Episode 7 is pretty soul-crushing in general, as Willard raised Yuliy and looked out for him as if he were the child he never had. Willard also regrets the things that he had done in the past and as a result, doesn't try making any excuses and tries to let Yuliy kill him.
  • What makes that scene even more heartbreaking is Yuliy's reaction. He is unwittingly sent into an Unstoppable Rage by the Big Bad and almost ends up attacking Willard, but realizes that he cannot bring himself to kill him as Willard was the one who raised him after his clan was massacred. Then he just breaks down in tears, asking why did his loved ones have to die.
• Mikhail's death, fullstop. In his last moments with Yuliy, he admits that he is happy to be able to die as this way he will be freed from the powers of the Vampires, that is, the same power that killed their mother. He then tells Yuliy that he is strong, as the light in his eyes fades away, signifying his death. Yuliy can do nothing but whisper out "that's obvious.... because I am your little brother!" and break down in tears as he lets out a last heartbreaking scream of "Nii-san!!!". Just... the whole scene is one big Tearjerker.
  • It's even more heartrending when you look at it from Yuliy's perspective. Basically, he just lost his beloved brother a second time.