Isekai no Mahou Gengo Ga Doumitemo Nihongo Dattaken

One day due to an accident, Okata Kazuhiko, a university student living in Japan, drew closed the curtains on his short life. In the world he reincarnated as Gerald, he discovered that, for whatever reason, the language of magic was Japanese.
Gerald, who had retained his memory, quickly grasped any spells due to his mastery of Japanese. Taking advantage of his unparalleled skill in Japanese, Gerald leaves his village in order to become the greatest magician the world has ever seen.
Author: TigerKitty, Torakoneko
Chapters: 64
Aliases:

No matter how you look at it, this world's magic language is Japanese, 異世界の魔法言語がどう見ても日本語だった件

Chapters

1-This world where magic can be used in Japanese
2-Memory of previous life
3-I learned the magic easily
4-Father's understanding and mother's love
5-Father's understanding and mother's love
6-Study magic
7-Erase charcoal soup
8-Practice magic
9-Cute creature
10-Let's go on an adventure!
11-First fight
12-Perception of magical power
13-Magic control and spell improvements
14-Invitation to play
15-omen
16-Monster attack
17-Father's decision
18-Kick off the demons
19-Filimina whistle
20-The smoky battle of the future
21-Prologue: Girl in the back alley
22-Adventurer Town Zet
23-Betting match
24-Small attack and defense of inn
25-Junior adventurer
26-First dungeon
27-Lunch rice and honey lemon
28-Fell
29-Lower → Intermediate   Most Lower → Lower
30-Examiner duties
31-Examiner
32-Wood dragon
33-Destroy a flock of dragons
34-Forest abnormalities and reports
35-Distribution survey
36-Investigation team
37-Half-year-old incident and Mayfan circumstances
38-Dreams and signs
39-After the training at Yuya
40-Magical Language Lecture by Professor Gerald
41-Encounter with the enemy
42-Fist thrown away, new light
43-Goblin strikes
44-Death battle with the demon
45-A slightly stronger enemy than Wood Dragon
46-Sword and fist
47-And settle
48-Types of strength
49-New house trap
50-Mat and foot
51-Noel's call
52-quarrel
53-That person, the court lead magician
54-New resident
55-Crawling
56-Demons and girls
57-Mir of face that does not float
58-I couldn't even say good words
59-Mir turning her back
60-Dissatisfaction, and concerns and worries
61-Ancient book
62-Illness and breather
63-Good friends
64-Court Leader Mage's Advice