Isekai wa Smartphone to Tomo ni.  

In Another World With My Smartphone, 異世界はスマートフォンとともに。

Touya Mochizuki was accidentally killed in our world, but God granted him a second chance at life by allowing him to be reborn into a fantasy realm. As an apology for his death, God gave Touya the ability to make one wish, which he chose to keep his smartphone with him in this new world. In his new life, Touya formed many important friendships and discovered the secrets of this world. He inherited the legacy of a long-lost civilization and traveled freely while possessing powers that rivaled those of the realm's kings.

Isekai wa Smartphone to Tomo ni. has been published digitally in English as In Another World With My Smartphone by J-Novel Club since March 23, 2017.