The Night Beyond the Tricornered Window: Volume 8

The Night Beyond the Tricornered Window: Volume 8 (Sankaku Mado no Sotogawa wa Yoru, さんかく窓の外側は夜) is the eighth volume in the The Night Beyond the Tricornered Window manga series by Tomoko Yamashita. It was released in Japan in book format on February 10, 2020 and is awaiting digital format for English by SuBLime.

Summary
"It's sad that you've always had bad feelings." A crypto memo arrives at the office of Reikawa and the triangle. It was a voice chat invitation from Erika. Erikka was able to hide herself from the cult. While the team was working together in an attempt to uncover the identity of "teacher," Siragawa alone was thinking of another thing. "It's good to go straight to stealing everything, money and power." A triangle that points out the poorness of Suzukawa's way of thinking, but he pulls that triangle cold and blows it to the Curse Pond...!?