170,000-Year-Old Cicada Larva (17万年ゼミ幼虫, 17 Man-nen Zemi Yōchū, Viz: 170,000-Year-Old Cicada Nymph) was a Mysterious Being that attacked Z-City at some point during Saitama's training years. It was killed by Saitama.
The Cicada Nymph was a massive cicada-like creature. It had the face of a child at the center of its head.
It was supposed to be a larva underground during the season it popped out.
Appearances in Other Media
During Saitama's training years, the Cicada Nymph attacks Z-City and defeats two C-Class heroes, Grad School Graduate and Red Muffler, and the B-Class hero Darkness Blade with ease while the rest of the population barricades itself within Shelter Nr. 7. Sometime later two unnamed A-Class heroes try to fight it, but are also defeated, which causes the Hero Association to declare it as a Demon-level threat and they decide to send one of their newly formed subjugation squads to finish it off. Saitama, while running around in search of a bathroom, runs into the Nymph who suddenly attacks him, but falls victim to Saitama's punch.
Abilities and Powers
It defeated two A-Class heroes which prompted the Hero Association to deem it as a threat with a disaster level of Demon.
Enhanced Strength: The 170,000-Year Cicada Nymph was a powerful Mysterious Being. It had enough strength to defeat multiple heroes, including two A-Class ones.
Enhanced Durability: The 170,000-Year Cicada Nymph was very durable. It was able to smash through buildings without visible damage.