Yamamoto Is My Daddy Sweatshirt

The phrase "Yamamoto Is My Daddy" on a T-shirt is a cultural and fan-driven expression of intense admiration, commonly used within fan communities of entertainment works like anime, manga, or comics (given the previous context of Japanese works, it's plausible this refers to a character or creator within that sphere).

To fully grasp its meaning, we need to analyze the wording and its contextual usage:

Breakdown of the Phrase:

"Yamamoto": This is a common Japanese surname. In this context, it refers to a fictional character (or sometimes a real person) whom the wearer intensely likes and admires. Based on previous interactions, this might allude to an author or character related to Yaoi/BL works, such as the creator MATSUO Isami whose work "Eto Irokoi Zoushi" was mentioned.
"Is My Daddy": This phrase is the core of the message and carries a meaning far removed from its literal interpretation (biological father).

Meaning within Fan Culture:

In fan slang, particularly within shonen ai/yaoi/BL fandoms, referring to a character as "Daddy" (or "Daddy Material") conveys the following:

Attraction and Authority: It expresses strong sexual attraction and admiration for the character due to their mature, masculine, authoritative, reliable appearance, or their ability to take charge. This character is often seen as an ideal type, someone who can control situations or possesses overwhelming charisma.
Protective Role: The term implies a desire for the fan to be cared for, led, or protected by this character.
Humorous Expression: Similar to the usage of "I'm Gay For Maye," the term "Daddy" is often used as a hyperbolic, humorous way to express extreme adoration for a character. It's an exaggerated fangirl/fanboy statement.

Summary of the T-shirt's Meaning:

The T-shirt "Yamamoto Is My Daddy" means: "I am extremely a fan of the character (or author) Yamamoto because of their overwhelming attractiveness, authority, and masculinity. I am completely captivated by this character."

This is a declaration of the fan's loyalty and passionate affection, utilizing slang prevalent in fandom culture to create a striking and attention-grabbing message.