|Common name||Plan B-tan|
|First appearance||Jan 2008|
|Height||160 cm (5'3")|
|Hair color||white with purple tips|
|Eye color||dark grey|
|Faction||User Space Gang|
|Lineage||Bell Labs research Unix (through Plan 9)|
|System personified||Plan B|
Plan B is an OS designed to operate on top of Plan 9 and focuses on distributed environments with variable amounts of resources.
Plan B-tan is incredibly resourceful and nonchalant, able to keep her cool and make do with whatever is around when resources are low. And while usually quiet, she is not adverse to speaking her mind. She resembles her 'mother' Plan 9-tan and has short but wild white hair with purple tips, dark grey and perpetually droopy eyes with black eyeshadow, wears minidresses with fin-like sleeves and a matching 'tail fin' skirt layer in the back. Her appearance is also based off of the Plan B mascot, an orange fish with purple fins and droopy eyes.
She often accompanies Plan 9-tan and writes down everything Plan 9-tan says, even if it is embarrassing.
Plan B-tan is Plan 9-tan's clone, created to assist her in managing the User Space Gang where she is affiliated. Being Plan 9-tan's clone, she could be considered Inferno-tan's sister. Possibly taking after Plan 9-tan, Plan B-tan created her own 'clone': Octopus-tan.