Foreword:

Rain of Terra is opus magnus of Ratatosk, an Azumanga detective crossover with Kiyohiko Azuma's other work, Yotsuba, inspired by Not-as-Thrilling-as-Advertised's The Other Takino, a similar crossover leaning more to Yotsuba. While TOT seems to be inspired by Adult Swim and the Internet, Ratatosk clearly states his inspirations being the detective fiction of Raymond Chandler and Dashiell Hammett. He's not particularly happy with the results after concluding it in 2012.

Author's description: Detective Tomo Takino is known for cracking the toughest cases. Now, Tomo and her partner Torako face their biggest, and most personal, case yet. Can they solve it without ruining their friendship?