Shibuya Halloween Goes Virtual This Year! Report on the “Halloween AI Costume Event” Showcasing PR Professionals’ Playful Spirit

As winter seems to arrive in the blink of an eye at this time of year, SUNNY SIDE UP GROUP held its first-ever in-house event this year: the “AI Costume Contest 2025”! It is a unique initiative in which participants use their Slack profile images and take on “costumes” with generative AI.

The purpose of this initiative is to bring out members’ creativity and playfulness, and to promote cross-department communication. In addition, by creating opportunities to use generative AI, it is also intended to help improve AI literacy.

A little strange, somehow funny, and something you will want to tell someone about—this kind of “costume commotion” broke out on Slack.

The theme was “Halloween” or “a costume that symbolizes 2025.” Participants generated and set a profile image of “themselves in costume,” then showcased it on Slack. Many of the submitted images incorporated timely topics and trends that were uniquely “PR-person,” and the entire group got excited.

DONQ’s Halloween Ghost Mini Croissants Appear in the Office!

To coincide with the event, the company also prepared a few treats to bring out the Halloween spirit in the office.

From Mini One, a brand of the long-established Kobe-born bakery “DONQ,” which is celebrating its 120th anniversary this year, special “Halloween Ghost” and “Mini Croissants” appeared in the central kitchen! It is also a brand for which SUNNY SIDE UP handles PR, and the seasonal surprise brought smiles to members’ faces.

The Halloween Ghost is a limited-time item filled with Hokkaido pumpkin cream and custard. It features a crispy texture and gentle sweetness. Along with the ever-popular mini croissants, it became a moment to enjoy seasonal flavors without leaving the office.

Slack Screen Filled with “AI Costumes”

The entries were created from “prompts” that members themselves entered into generative AI. This initiative, which tests imagination, humor, and a little courage (?), drew many participants from across the company.

This year, the MVP was decided by an internal vote based on criteria such as “Does it match the theme?”, “How interesting is the idea?”, and “Visual impact.” The winner received TENTIAL’s recovery wear “BAKUNE” as a prize!

MVP Winner Interview

This year’s MVP was awarded to Ms. Mizukami, who usually plays an active role as a member of the HR and General Affairs Department!

Based on the unique theme of an “AI zombie,” she gathered votes with a story-driven costume: herself as a mummy wrapped in yarn, and another version of herself “luring a friend into the world of mummies.”

🏆 Winner’s Comment: Ms. Mizukami

“When I tried the prompt twice, the theme ‘AI zombie’ was generated first. I found the idea of humans being gradually infected by AI interesting, and expanded my concept from there.

Knitting also happened to be a trend for me at the time, so I requested a mummy-like visual wrapped in yarn. I also set it up as if a friend were luring me into the world of mummies.

It is not exactly ‘the mummy hunter becomes a mummy,’ but there is also an underlying theme of valuing our humanity without losing to AI. I am very happy to receive this award!”

TENTIAL’s fatigue-recovery pajamas “BAKUNE” presented as a prize!

For the winner,with the hope of helping them regulate a sleep rhythm that can easily become disrupted during long autumn nights,BAKUNE Dry Women’s from TENTIAL’s popular recovery wear “BAKUNE” series was presented.

Made with the proprietary special functional fiber SELFLAME®, this recovery wear promotes blood circulation and supports fatigue recovery. It has also been registered as a general medical device (“home-use far-infrared blood-circulation-promoting garment”). It is a piece that helps create a comfortable sleep environment and supports healthy everyday life.

Wear that thoroughly relieves the day’s fatigue and helps you sleep soundly is perfect even for a body “tired out from playing with AI costumes (?)”.

Through this first-ever AI costume contest, the “fun commotion” that unfolded across Slack screens seems to have created some new connections that crossed departments and seniority levels.

We are already looking forward to seeing what kinds of AI costumes will appear next year. We encourage everyone to enjoy AI costumes as well!