Mitsuba's parents

Mitsuba's father (ミカエラの父) and Mitsuba's mother (ミカエラの母) were the parents of Aoi Sangū and Mitsuba Sangū in the Seraph of the End series.

History
At some point, they met one another and had Aoi, then Mitsuba as their daughters. Through some means, likely on account of the catastrophe effects, they passed away. From this their bodies would be collected and kept somewhere for eight years. While they could have been there for the time passed, their bodies would be stored in pipe fitted coffins underground Akihabara, where they were kept alongside many others. These included coffins containing Tomoe Saotome, as well as Yu and Mika's Hyakuya Orphanage Family.

Events of 2020
Upon arrival in Akihabara, Category:Shinoa Squad squad along with the vampires accompanying them enter an elevator to take them fifteen floors underground to a laboratory. There are countless coffins but with arrows drawn on the floor, with directions for Mitsuba and Yoichi rightwards. Approaching a see through coffin with pipes fitted to it, Mitsuba is stunned to find her parents.

Their potential resurrection is discussed at this point. Where a resurrection has occurred before, their fates would be influenced by Yu, who was given an ultimatum to restore Mika only, or use the spell to resurrect all of humanity which would include them both.

Mitsuba Sangu
Their second daughter, it is unlikely they would know she becomes a member of the Moon Demon Company. Specifically a part of Shinoa Squad, she would wield the Cursed Gear named Tenjiryū, currently active around them.

Aoi Sangu
Their eldest daughter who attended First Shibuya High School. Their knowledge that Aoi survived the attack on First Shibuya High School is unknown, but on account of their passing, they may certainly not know she would serve Kureto Hīragi, the Lieutenant General of the Japanese Imperial Demon Army after the world ended.

Guren Ichinose
A Lieutenant Colonel of the Japanese Imperial Demon Army, and leader of the Moon Demon Company. It is very likely that the Sangu parents were gathered at his direction. Their resurrection is favored by him.

Yūichirō Hyakuya
Based on current events, if they are not restored to life it would be on account of Yu's actions.