This manga is where main character gets isekai'd to a new world. This dying man wants to give him his own magic to make him a successor.
After the man dies the main character used creation magic to move the man's soul into a frog. The manga is in black-and-white and the magic is magic that can create new magic.
This is Ore to Kawazu-san no Isekai Hourouki (AKA Chronicles of My Adventures in Another World With Kawazu-san).
Tarou was an ordinary university student until a strange old magician summoned him to another world, upon learning that his magical power is 8 million, he uses that abnormally powerful magic to revive the old man that caused all this... In the form of a frog. Thus begin the strange adventures of a boy with ridiculous magical power and Kawazu, the former strongest magician, now revived as a frog.
