Haha Ranman by Alice Soft (Eng/Jap)
Losing the will to live, Mayuko had fallen into despair and tried to kill herself, but there was a young boy who pulled her heart away from the despair. His name is Kaga Isamu. Like Mayuko, his parents also lost their life to a sword killer.
Mayuko felt a connection between them, decided to adopt Isamu from orphanage and started living together.
alice soft male protagonist adult heroine non-blood-related mother as a heroine mystic romance drama