Before, Zetsubou-sensei said like 人は本筋以外のところが気になるものなのです[Anything else but the main point actually interests people]. That might be true. Come to think of it, I have seen something like that a lot. The more characters, the more popular other supporting characters would be. Even get more popular than a lead character. Of course, doujin fans sure create countless stories with their own favorite characters from the series, however, when a certain character(not a lead) gets very popular there would be a spin-off story or work…That is 外伝[gaiden] or 外伝もの[gaidenmono] or side story.
We say 二次創作[nijisousaku] to mean such a fan-made story, but unlike this, 外伝 would require an agreeable storyline for the sheer fans. Besides, it ought to unveil something that is supposed to be veiled in the main plot. For example, in the main story, the character was an enemy and died in the battle. But his fans would like to know why he was an enemy and what had happened before he showed. Focused on the character, another story begins…that is 外伝もの[gaidenmono]. It is not uncommon that 外伝 gets more popular than the main story. Speaking of 外伝, I can definitely think of L change the World, which is a spin-off film of Death Note. Needless to say, this film focuses on L, and features another story. Neither Light nor Misamisa shows, so that means it can spare much time for L. His fans are as happy as can be…
My favorite 外伝 is Trunks the Story[トランクス・ザ・ストーリー～たったひとりの戦士] in Dragon Ball. In the main plot, Trunks comes from the future world to save Goku because Goku is supposed to be dead out there. Android no.17 and no.18 massacre people, so that is why Trunks tries to save Goku who is going to die from heart disease. Trunks is not such a big part, but the side story is really nice. It clearly shows what had happened to Trunks before he showed, and features what he had experienced…how pathetic the world he had been in…Because there are basically a few characters in the side story, it could unfold the story more. In fact, there are just Trunks, Bulma, and Gohan most of the times in the episode.
Oh speaking of which, if you follow Ace Attorny[逆転裁判], you would be sure of 逆転検事[gyakuten kenji], which features Prosecutor Mitsurugi Reiji[御剣怜侍]. This time, the lead is him! I wonder how many his fangirls are screaming in joy? Actually, I prefer him than Naruhodo-kun.^^ I bet this upcoming game would do better than the previous series.