The Solemn are a species of humanoid creatures in the Antiverse. Following the global collapse of Re-L's infrastructure through resource depletion and usage of mega-weaponry, only few were capable of making their way off the now anarchic atmosphere. LOGO's logs regarding survivors state that 118 Solemn were capable of successfully making their way off the planet. Additionally, no signs of intelligent life on Re-L are present.
Hundreds of years of biotechnical progression have refined the Solemn's bodies to extremely malleable products, allowing them manual control over various components of their vessels. This leads to the theory that by slowing their metabolism, they are capable of surviving millenia, meaning that many of the survivors of Re-L's downfall could still be alive. In combination with their extremely energy-effecient bodies, there are few reasons to assume that none of them remain, aside from suicide.
In fact, LOGO confirms having spotted at least two solitary drifters on separate occasions. The remaining survivors have no contact with one another, suggesting questionable mental health stability for those who have deliberately not gone into metabolic stasis. The fact that the Antiverse is in its intermediate stages of heat death doesn't help, as the quantity of planets capable of supporting life is quickly dwindling. As it stands, any Solemn survivors are destined to eternal solitude.