You can report slanderous acts or copyright infringement to Cover at this link:
https://cover-corp.com/report/en/

You only need a name and email address to send a report. This is the report I sent.

In MORI CALLIOPE-san's recent stream 「【NEW SONG PARTY】I'm Trapped in the Closet.」, MORI CALLIOPE-san said that there was currently a party being thrown at her lodging, where MORI CALLIOPE-san and GAWR GURA-san were staying the night. At 09:27, MORI CALLIOPE-san states, 「There was a rager going on, like, full-on EDM blasting out the windows. I was like yo, we're gonna get kicked out.」「And... I was just kinda like, awkwardly there, but at the same time, everyone was like 『Calli, you got this fantastic place?』and I'm like 『Yes I did and I want to keep it clean for my friends that are coming.』And they were like 『Oh! ... Anyway, I'm trippin balls right now.』」

Note: a「rager」is a type of party with drugs and alcohol, typically involving many people. EDM is commonly played at parties where drugs can be found.
Note: 「I'm trippin balls right now」means 「I am high on drugs right now.」

MORI CALLIOPE-san goes on to say, at 10:24,「I was like 『Look, the only way I can be here is by being a v-tuber.』」At 12:13, she states, 「I think 『GAWR GURA-san』's fine right now. I think that she's... she's in a room close to me, away from where the speakers do be bumpin. So I think she's fine. She was just like 『No no no, it's cool, I'm just gonna sleep.』So she's sleeping. Um, but I don't know. She could be up to some other shenanigans. Who could say?」

Note: 「the speakers do be bumpin」means 「the speakers are playing loud music.」
Note: 「Shenanigans」means 「mischievous behavior.」

MORI CALLIOPE-san is endangering GAWR GURA-san's safety by bringing her to a dangerous environment full of unknown people, a 「rager」, and MORI CALLIOPE-san says that this place has drugs in it.

MORI CALLIOPE-san slandered GAWR GURA-san when she implied that GAWR GURA-san may be using illegal drugs or engaging in「shenanigans.」

In the United States, party drugs are commonly laced with Fentanyl, a highly lethal synthetic opioid. Fentanyl is 50-100 times stronger than morphine. When party goers use drugs such as cocaine at parties, the drug user can mistakenly take a lethal dose of Fentanyl, and die.

It is highly irresponsible for MORI CALLIOPE-san to endanger GAWR GURA-san by bringing her to a party where illegal drugs are being used. It is slanderous for MORI CALLIOPE-san to say that GAWR GURA-san may be engaging in mischievous shenanigans at the party, because this implies that GAWR GURA-san may be taking illegal drugs.

It is my understanding that GAWR GURA-san did not know the party would be taking place. MORI CALLIOPE-san knew the party was happening there and decided to use that place as a lodging for GAWR GURA-san.

Please do something about this reckless behavior. The health of the talents is in danger.