It appears to be a living bathtub or washing machine with a round head bearing a blank expression, and a small bird sitting in its water-filled body, along with a crank like tail. It resembles a turtle.
Woshua speaks in short sentences and seeks to make everything clean due to it being a hypochondriac. As such, it constantly suggests to the protagonist that they clean themselves, especially before touching it. Its germaphobia goes as far as hating "dirty jokes," and it appears to find Moldbygg a heavily unclean monster that it will flee from the protagonist if they hugged Moldbygg then attempted to touch Woshua.
- Spiraling patterns of water-drop bullets branch out from the center of the Bullet Board.
- If attacking with other monsters, these bullets are light blue.
- A soap-bar projectile with the word "HOPE" on it moves across and bounces on the sides of the Bullet Board, leaving trails of shining bullets that disappear after a short time.
- The protagonist must ask to be cleaned to spare Woshua. This adds three Healing green bullets to Woshua's water drop attack. If the protagonist allows Woshua to heal them, it becomes pleased with its cleaning and allow the protagonist to spare them.
- If the protagonist chooses the action "Touch" while they are unclean, Woshua rejects this action and attacks the protagonist as normal. If the protagonist is cleaned while trying to touch Woshua, they give it a friendly pat.
- It is also possible to make Woshua flee by hugging Moldbygg, then touching Woshua.
- Telling a joke disgusts Woshua, reducing its attack.
- tweet [Neutral, only said by the bird on Woshua]
- Wosh u face [Neutral]
- Wosh u hand [Neutral]
- Wosh u leg [Neutral]
- Wosh u teeth and eyes [Neutral]
- Scrub a dub-dubs [Neutral]
- Oops, I meant... scrub a sub-SUBS [Neutral]
- *whistle as it cleans* [Neutral]
- Out!!! Darned spot [Neutral]
- Wosh u SOUL [Neutral]
- Your SOUL is unclean. [Neutral if kill count is greater than 0]
- Yuck! [Touch]
- Fresh! [Touch after being cleaned]
- Green means clean [Clean]
- NO. THAT JOKE'S TOO... DIRTY [Joke]
- Napstablook's remix Easter egg (With Aaron)
- If the protagonist turns on one of Napstablook's music CDs and heads outside, they encounter Woshua and Aaron, and trigger this Easter egg. After it is complete, shooing Aaron causes him to leave the battle.
- [Woshua] ... what the HECK is that music?
- [Aaron] I-I DUNNO DUDE, BUT IT'S SPOOKIN ME OUT ; )
- [Woshua] ... this is worse than Shyren.
- [Aaron] No way, Shyren is way less scary ; )
- [Woshua] ... if you're so scared, why do you keep winking?
- [Aaron] THESE ARE WINKS OF FEAR ; )
- [Woshua] Forget it. This beat is too... ... filthy.
- [Aaron onward] Wosh! Wait! Don't leave me ; )
- Is this creepy music my punishment for being creepy? ; )
- Please... stop... I'll never creep again ; )
- Wahhhhh!!!!! ; )
- This humble germophobe seeks to cleanse the whole world. [Check]
- Woshua shuffles up. [Encounter]
- You shouldn't read this. [Encounter with Aaron on the left]
- Woshua and Aaron appear. [Encounter with Aaron on the right]
- Moldbygg and Woshua appear. [Encounter with Moldbygg]
- Woshua is friends with a little bird. [Neutral]
- Woshua wonders if tears are sanitary. [Neutral]
- Woshua is rinsing off a pizza. [Neutral]
- Smells like detergent. [Neutral]
- Woshua is looking for some good clean fun. [Neutral]
- You ask Woshua to clean you. It hops around excitedly. [Clean]
- You give Woshua a friendly pat. [Touch after successful Clean]
- Woshua is terrified of your slimy body! It runs away. [Touch after Hug on Moldbygg]
- You tell a joke about a kid who ate a pie with their bare hands. [Joke]
- You tell a joke about two kids who played in a muddy flower garden. [Joke]
- You tell a joke about a kid who slept in the soil. [Joke]
- Woshua's powers are neutralized! [Joke]
- You reach out. Woshua recoils from your touch. [Touch before Clean]
- Woshua is revolted at its own wounds. [Low HP]
- Woshua's name is a combination of wash and the name Joshua. Their name also could be a corruption of "Wash You" (Wash You → Wosh Ya → Woshua)
- Its name can also be derived from the Chinese phrase 我刷 (wǒ shuā), meaning "I brush."
- The line "Out!!! Darned spot," is a reference to a scene in Shakespeare's Macbeth. In the scene, Lady Macbeth begins to believe that she has a bloodstain on her hand when there is none, and exclaims "Out, damned spot! Out, I say!"
- Woshua saying "Scrub a dub-dubs" before correcting to "scrub a sub-SUBS" is a reference to the sub vs. dub debate, one of the oldest debates in anime fandom.
- The sound that Woshua makes when it is hurt is the same as Flowey's sound when he is being hurt.
- Woshua's face bears a striking resemblance to the MS Paint Adventures logo, home of Homestuck, where Toby Fox contributed as a music producer.
- The flavor text that appears upon joking appears to allude to the story of the fallen human and Asriel.
- With the exception of the Amalgamates, Woshua is the only monster who displays two quotes at the same time.
- After completing Waterfall, Woshua appears at the beginning of the Garbage Dump, stating that it is cleaning the trash and sorting it into symmetrical piles – "It's hard work, but somebody has to do it."
- Woshua can also be found in "The War of Humans and Monsters" story hallway, stating that if it could, it would erase the whole world because everything is so dirty: "Ohhh. Don't get the wrong idea. I don't want anyone to die. When people die, they turn into dust and that's hard to clean up." If spoken to again, they say, "Don't turn to dust."
- Before version 1.001, Woshua's Stats were "ATK 7 DEF 1."
- Entering the name "Woshua" for the fallen human causes the game to describe it as a "clean name," and allows the name to be used.
- Woshua is mentioned during Mettaton's news report by the headline saying "WOSHUA CLEANS UP LOCAL CRIME, LITERALLY, FINDS CRIMINALS AND DOUSES THEM IN SOAP, CRIME DOESN'T GO DOWN BUT IT SMELLS AMAZING".