|Cause of Death||Presumably natural causes|
Little is known about Guertena's appearance. All theories state that Guertena was either middle-aged or an old man before he died. On the recent version of Ib, a portrait of him is displayed, yet his face isn't shown; therefore, the mystery of Guertena still remains.
Very little is known about Guertena, though it seems he was a skilled and passionate artist having an entire museum for just his work alone. In fact, his work was so good that some of it came to life, implying he may have some magic in his background. This does not appear to have pleased him, as in A Painting's Demise, it's implied he keeps a close eye on the main characters and will kill them if they leave without meeting the appropriate requirements.
- In his self portrait, Guertena can be seen holding a paint brush in his left hand, which hints that Guertena might be left-handed.
- The picture that he is painting is the portrait of Mary.
Below is a list of compiled ideas and theories about the game.
- Garry is Guertena. Though this theory is just a thought, people gave this attention as they try to realize the idea.
- However, the lady in black standing near the Fusion statue in the Guertena Art Gallery mentions that Guertena is, indeed, dead.
- Also, the book about Mary's true identity in the Violet Area mentions that the Mary painting was the last one that Guertena had painted in his life, hinting that Guertena had already passed away.
- Additionally, the sign in the room with the Abyss of the Deep painting in the Guertena Art Gallery says, "We hope you deeply enjoy the art of the late Guertena," indicating that the exhibition is held after Guertena's death.
- Garry is Guertena's grandson (mentioned in the "Complete Works of Guertena (Part I)"). That would explain how he knows the year the Juggling painting was made (because he was with Guertena at the juggler's performance).
- Guertena painted Mary as a memory of his daughter or his "dream" daughter. A lot of theories stated that he based it on his painting The Lady in Red. Fans also followed this theory.
- This theory became less believable when Mary mentioned that the Lady in Red was her "sister" after a newer version of Ib was released.
- Mary could not be a memory of Guertena's daughter, as the book about her true identity in the Violet Area stated that she was not based on any real person. The man looking at The Lady in Red painting in the Guertena Art Gallery also mentioned that Guertena was known to not paint real people.
- Guertena had a past relationship with Ib. Any child with a huge imagination could enter the cursed gallery. Why Ib? The thought came to people, trying to connect the paintings and Guertena, one by one.
- Also, the woman in the The Lady in Red painting looks very similar to Ib and her mother (Garry actually mistakes Ib for one of them when they meet). This painting is also said to have been based on the gold-digging women Guertena has encountered in his life. Ib's mother may have been one of those women, and Guertena may have lured Ib into the gallery to teach his past lover a lesson.
- However, the ability to enter the cursed gallery has nothing to do with being a child with a huge imagination; thus, not just any child can enter. The cursed gallery presumably chooses people based on people's spirits. Possibly tied with the Embodiment of Spirit sculpture, the ability to enter the cursed gallery depends on the person's spirit. According to the plaque near the Embodiment of Spirit, "it can only bloom in wholesome bodies," meaning that a representative rose can only bloom for a person whose spirit is whole; thus, the person must have a wholesome spirit to be able to enter the cursed gallery. This means that Ib was able to enter it because she has a wholesome spirit, as does Garry.
- Also, since Garry, an adult, was able to enter the cursed gallery, being a child is irrelevant to the subject of being able to enter it.
- Additionally, Ib's mother likely could not have been one of the gold-digging women after Guertena or his past lover, as Guertena and Ib's mother have an age gap of at least one generation. Guertena is implied to be an old man before he passed away, while Ib's mother seems to be young or middle-aged. Also, the Lady in Red and Ib's mother may look similar to each other only because they are rich women or ones with high-class taste.
- Something is wrong with Guertena himself. Despite the fact that his paintings are constantly praised, it was theorized that he had extreme emotions while painting his art. This led to the solution for why the paintings moved on their own.