The site's main title "Basement Boys" is supposed to be a reference to the Japanese term "地下アイドル" which translates into "Underground Idols", meaning idol groups or bands that have not had a "major" debut and are thus not 'official'. It can be considered as a sub-genre of the "indies genre", which encompasses all styles of music and all types of groups. The name was derived from the venues these kinds of groups use, which are located underground as opposed to the big concert halls and venues used by the major, mainstream artists.
As the title says, this website will be dealing with male groups mostly (地下メンズ 'chikamens' in Japanese, derived from 地下メンズアイドル 'chika men's idol') and will aim to provide some general information about the genre itself on the side as information about it can be a little scarce still in the international fandom.
As maintaining and especially updating all of the individual sites takes a lot of time, I decided to open a blog where I talk about recent developments (or just other random stuff).
Despite the name "Underground Idol" the genre has split into a few sub-categories in the past few years and the "Underground" label has now become almost synonymous to the indies one, although indies is still the official term used at CD shops.
Originally the label "Underground Idol" was used for female groups as male groups were rare but in recent years more and more male groups started to appear and garner a lot of attention. Some of them have even made it to 'major' status and have thus 'surfaced' (notable examples: B2 Takes, whose name is a nod to their 'basement' origins and MeseMoa).
Roughly speaking, the genre is subdivided into the following three categories: Dance & Vocal Units, Idol Unis and Solo Artists.
Dance & Vocal units are classified by the clear division of roles between the members, some members are vocalists, some are exclusively dancers/performers. This style of group underlines individual strengths.
Idol Groups, compared to dance & vocal units, do no have a clear division of roles. All members are supposed to be able to sing and dance and many songs include parts sung by all members as well as fan-chants targeted towards the whole group or individual members.
Solo Artists, as the name implies, are artists who do not belong to any group or unit.
Other notable differences between the different sub-categories can be found in the fan behaviour and fan involvement. While there is some overlap (e.g. 'member colours/image colours'), there are also very big differences. One being the use of penlights and the existence of the so-called 'fan-chants' (not to be mistaken for what is called "Call & Response", which is somewhat related to chants but not the same).
Penlights are used at (almost?) every idol concert that I have been to or seen on DVD or TV. Most concerts sell penlights as part of their concert goods lineup and the penlights will be customized to a certain degree, be it a certain design or just a certain lineup of colours to match with the group (every member of the group has an image colour, or 'member colour'). Fans usually use the colour of their favourite member (called 推しメン oshimen or short 推しoshi, which can be roughly translated as 'member I am supporting' or lit. 'pushing').
At major idol concerts I have been to the usage of penlights was different from how they are being used at Underground Idol events I have been to. It's an interesting difference really but could also be considered slightly annoying. Here's what happens: during regular idol events, most fans will use the colour of their favourite member during songs their favourites are on stage. Everyone has to hold their penlights at a certain height only as to not obstruct the view of the people behind them. During solo songs, everyone turns their penlights to the colour of the member performing. During Underground Idol events I saw that people raise their penlights above their heads and move them back and forth in a loop motion when their favourite member is singing a solo part in a song. That way you can clearly see who supports whom but the up and down movements are a bit exhausting for people who just want to watch the show as your view might get blocked for a few moments at a time.
A lot of Underground Idol songs have set fan-chants and these chants can either be 'general chants' or 'original chants'. General chants are the same across the genre or at least a certain number of groups. You will hear the same chants in multiple songs and multiple groups will use the same chants. The only things that change are the members' names of course.
Original Chants are used by only one group and are sometimes also tied to only a single song (for example the one shown in the screenshot).
Fan-Chants are different from "Call & Response" in that fans will do these chants automatically without being prompted by the performing artists. A "Call & Response" always comes with a cue given by one of the performers. Fan-Chants can be cued by performers but a Call & Response cannot be initiated by fans.