Operation Abyss: New Tokyo Legacy

There are a total of 17 Wanted Variants in the game. As you progress through the game, more Wanted Variant sub-missions become available to you. Wanted Variants roam in specific sections of specific dungeons. They appear as random battles and they can even appear as "forced" battles in dungeons. They are more dangerous than the regular enemies in the dungeons but if you can easily clear out the regular enemies, you shouldn't have much trouble with the Wanted Variants if you fight them like bosses. These missions carry over so you don't have to complete all of them before going to the second semester; they will still be available in the second semester though sometimes in a different location. You have a better chance of getting a Wanted Variant with a higher Encounter Gauge.

Siren ~ Morimoto High-rise
Ogre ~ Gakuto Sewer B2F [1st semester] or Morimto High-rise [2nd semester]
Tommy Mountain ~ Kagura District - NE(Top) [1st semester] or GHQ Cemetery [2nd semester]
Ultra Goblin ~ TPF Kingdom B3F
Death Scythe ~ Nihowa Abyss Sector U [1st semester] or TPF Kingdom B3F [2nd semester]
Rare Drill ~ Babyl Sphere N1 [1st semester] or Gakuto Sewer B1F [2nd semester]
Muvo Ω Pyroman ~ Babyl Sphere C3
Mega Drill ~ Babyl Sphere S2 or S3 [1st semester] or Gakuto Sewer B2F [2nd semester]
Voltrus ~ Kagura District - Central(T1)
Ultra Troll ~ TPF Kingdom B1F
Silver Turtle ~ TPF Kingdom 1F
Master Torture ~ Haunted Hospital 1F
Master PD ~ Xth Subway Line Outbound
Algol ~ GHQ Cemetery - Demon Area
Grand Buster ~ Geomatrix Σ
Derracotta ~ Nihowa Abyss Sector M
Wyvern Ω M ~ Babyl Sphere C6, C12 or C24