Their previous logo depicts a mouthful of teeth, with the four "e" representing both the number of members and their dental background, as all of them graduated from the Faculty of Dentistry.

"[3] All members of Gre4n Boyz attended the dentistry department at Ohu University in Koriyama City, Fukushima Prefecture.

Throughout their career, none of the members have ever revealed their faces in any public appearances, be it in promotional videos, CDs, television performances, or online platforms.

As a result, Gre4n Boyz's faces have never been made public, fueling speculation and curiosity among fans about the individuals behind the music.

HIDE began his music career as a member of a Japanese hardcore band in his junior high school.

After the group independently released their self-titled EP, Greeeen on February 14, 2006, Universal Music Japan recruited them in March 2006.

The song was certified Two Million by the Recording Industry Association of Japan (RIAJ) for 2,000,000 full-track ringtone digital downloads (Chaku-Uta Full).

[23] At that time, all members of GReeeeN, who witnessed the damage caused by the 2011 Tohoku earthquake and tsunami in their hometown of Fukushima, started this project with the idea that "At this moment, music may be able to help relax, warm, or encourage someone."

First, "Green boys" will be distributed free of charge for a limited time (until September 30, 2011), as well as Japanese, English, Spanish, Chinese, Taiwanese, and Korean.

In 2014, the band released their sixth studio album, "Ima kara Oyayubi ga Kieru Tejina Shimasu."

One single released from the album, "Shinobi", was used as the opening theme for the Japanese dub of Teenage Mutant Ninja Turtles.

The band became fully inactive until March 19, 2024, when they announced a significant change by altering their name to GRe4N BOYZ upon leaving their previous agency, High Speed Boy.

Initially, the group suggested they would unveil their identities after all members passed the 2009 dental license exam; however, they later opted to maintain anonymity to prevent any disruption to their careers as dentists.

During the early collaboration between HIDE and navi, they recorded vocals with the assistance of JIN's band, producing a mixture rock style heavily influenced by Western acts such as SUBLIME and SUGAR RAY.

Although their musical roots initially leaned towards pop, HIDE and navi decided to explore a mixture genre to align with their evolving tastes.

Upon SOH joining in 2004, their musical direction shifted to incorporate the sensibilities of all four members, blending elements from diverse genres including rock, breakbeats, hip hop, reggae, and J-pop.

Their debut single "Michi" serves as a quintessential example of Gre4n Boyz's musical fusion, combining breakbeats and band sounds with piano, emotive melodies, and harmonies from all four voices.

The hallmark of Gre4n Boyz's lyrical style is its ability to deliver messages that resonate deeply with listeners' hearts, a characteristic referred to as "GReeeeN Music."

Their lyrics are characterized by simplicity, driven by the desire to convey messages directly to the listener in a way that evokes empathy and understanding.

According to navi, each individual has their own unique circumstances, but the universal appeal of Gre4n Boyz's lyrics lies in their ability to connect with listeners on a personal level.

By using lyrics and melodies as a form of communication, Gre4n Boyz creates moments where listeners can find solace and understanding in their own experiences.

This collaborative effort underscores the depth and authenticity of Gre4n Boyz's songwriting process, reflecting the collective experiences and perspectives of the group members.