Parody of yesterday's live streaming on Nico Nico Douga.
To celebrate Miki's birthday, the voice actors of the above characters (wearing those outfits) made a "cake," which was supposed to be a mountain of onigiri. But they got too ambitious, and created a "suicide cake." Basically a disastrous mix of rice, cucumber, dried seaweed, pickled radish, umeboshi, furikake, ketchup, and etc. They practically made a yami nabe in onigiri form. Haruka's voice actor took two bites, and Miki's completely chickened out.