Despite the series' futuristic setting, Suga claimed that he aimed to give the audience modern themes to see in the anime.
[1] Suga, the most important writer in the 2007 Darker than Black series, handles high concept and main plot related arc, with Hei on the spotlight.
[2] For the 2010 original video animations Darker than Black: Gaiden Tensai Okamura gave Suga complete freedom and all he asked was that a scene with rain be put in.
For the latter, Suga went to Eastern Europe and created East Slavic Republic, a fictional post-Soviet country formed following the dissolution of the Soviet Union.
Upon his death, Kenji Kamiyama wrote that he was glad he met Suga as he often helped him in his works and had a kind personality.